Methods and apparatus are presented for identifying the presence of shunts in a first sub- cell of a multi-junction solar cell having monolithically integrated first and second sub-cells. The multi-junction cell is illuminated with light suitable for generating luminescence from the second sub-cell, while generating substantially no excess charge carriers in the first sub-cell. First and second images of luminescence generated from the second sub-cell with the multi-junction solar cell under different load conditions are acquired and compared to identify the presence of shunts in the first sub-cell.
H01L 31/06 - SEMICONDUCTOR DEVICES NOT COVERED BY CLASS - Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier
H01L 31/078 - SEMICONDUCTOR DEVICES NOT COVERED BY CLASS - Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier including different types of potential barriers provided for in two or more of groups
H02S 50/10 - Testing of PV devices, e.g. of PV modules or single PV cells
09 - Scientific and electric apparatus and instruments
Goods & Services
Apparatus for inspecting semiconductor materials including
wafers; apparatus for inspecting photovoltaic cells,
photovoltaic devices and photovoltaic modules; apparatus for
inspecting bulk silicon, silicon wafers and silicon devices;
apparatus for testing semiconductor materials and
semiconductor devices including photovoltaic devices;
apparatus for inspecting semiconductor materials and
photovoltaic devices using luminescence imaging; diagnostic
apparatus, not for medical purposes; apparatus for diagnosis
of defects in semiconductor wafers, photovoltaic cells,
photovoltaic devices and photovoltaic modules; software for
processing images of semiconductor materials including
wafers; software for processing images of photovoltaic
cells, photovoltaic devices and photovoltaic modules;
software for automating the acquisition and analysis of
photoluminescence and electroluminescence images; software
for automating the analysis of photoluminescence and
electroluminescence images using machine learning; software
for integrating apparatus for inspecting semiconductor
materials into fully automated production lines according to
automated metrology and optimisation of semiconductor
manufacturing lines.
09 - Scientific and electric apparatus and instruments
Goods & Services
(1) Apparatus for inspecting semiconductor materials including wafers; apparatus for inspecting photovoltaic cells, photovoltaic devices and photovoltaic modules; apparatus for inspecting bulk silicon, silicon wafers and silicon devices; apparatus for testing semiconductor materials and semiconductor devices including photovoltaic devices; apparatus for inspecting semiconductor materials and photovoltaic devices using luminescence imaging; diagnostic apparatus, not for medical purposes; apparatus for diagnosis of defects in semiconductor wafers, photovoltaic cells, photovoltaic devices and photovoltaic modules; software for processing images of semiconductor materials including wafers; software for processing images of photovoltaic cells, photovoltaic devices and photovoltaic modules; software for automating the acquisition and analysis of photoluminescence and electroluminescence images; software for automating the analysis of photoluminescence and electroluminescence images using machine learning; software for integrating apparatus for inspecting semiconductor materials into fully automated production lines according to automated metrology and optimisation of semiconductor manufacturing lines.
09 - Scientific and electric apparatus and instruments
Goods & Services
Apparatus for inspecting semiconductor materials including wafers; apparatus for inspecting photovoltaic cells, photovoltaic devices and photovoltaic modules; apparatus for inspecting bulk silicon, silicon wafers and silicon devices; apparatus for testing semiconductor materials and semiconductor devices including photovoltaic devices; apparatus for inspecting semiconductor materials and photovoltaic devices using luminescence imaging; diagnostic apparatus, not for medical purposes; apparatus for diagnosis of defects in semiconductor wafers, photovoltaic cells, photovoltaic devices and photovoltaic modules; software for processing images of semiconductor materials including wafers; software for processing images of photovoltaic cells, photovoltaic devices and photovoltaic modules; software for automating the acquisition and analysis of photoluminescence and electroluminescence images; software for automating the analysis of photoluminescence and electroluminescence images using machine learning; software for integrating apparatus for inspecting semiconductor materials into fully automated production lines according to automated metrology and optimisation of semiconductor manufacturing lines.
Methods and systems are presented for analysing semiconductor materials as they progress along a production line, using photoluminescence images acquired using line-scanning techniques. The photoluminescence images can be analysed to obtain spatially resolved information on one or more properties of said material, such as lateral charge carrier transport, defects and the presence of cracks. In one preferred embodiment the methods and systems are used to obtain series resistance images of silicon photovoltaic cells without making electrical contact with the sample cell.
Apparatus and methods are presented for determining the condition of photovoltaic modules at one or more points in time, in particular using line-scanning luminescence imaging techniques. One or more photoluminescence and/or electroluminescence images of a module are acquired and processed using one or more algorithms to provide module data, including the detection of defects that may cause or have caused module failure. Also presented is a system and method for determining the condition of photovoltaic modules, preferably throughout the production, transport, installation and service life of the photovoltaic modules.
G01N 21/66 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
G01N 21/88 - Investigating the presence of flaws, defects or contamination
Methods and systems are presented for analyzing semiconductor materials as they progress along a production line, using photoluminescence images acquired using line-scanning techniques. The photoluminescence images can be analyzed to obtain spatially resolved information on one or more properties of said material, such as lateral charge carrier transport, defects and the presence of cracks. In one preferred embodiment the methods and systems are used to obtain series resistance images of silicon photovoltaic cells without making electrical contact with the sample cell.
Embodiments of methods and systems for identifying or determining spatially resolved properties in indirect bandgap semiconductor devices such as solar cells are described. In one embodiment, spatially resolved properties of an indirect bandgap semiconductor device are determined by externally exciting the indirect bandgap semiconductor device to cause the indirect bandgap semiconductor device to emit luminescence (110), capturing images of luminescence emitted from the indirect bandgap semiconductor device in response to the external excitation (120), and determining spatially resolved properties of the indirect bandgap semiconductor device based on a comparison of relative intensities of regions in one or more of the luminescence images (130).
G01N 21/66 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
G01N 21/956 - Inspecting patterns on the surface of objects
G01N 21/95 - Investigating the presence of flaws, defects or contamination characterised by the material or shape of the object to be examined
Methods (600) and systems (100) for inspecting an indirect bandgap semiconductor structure (140) are described. A light source (110) generates light (612) suitable for inducing photoluminescence in the indirect bandgap semiconductor structure (140). A short-pass filter unit (114) reduces long-wavelength light of the generated light above a specified emission peak. A collimator (112) collimates (616) the light. A large area of the indirect bandgap semiconductor structure (140) is substantially uniformly and simultaneously illuminated (618) with the collimated, short-pass filtered light. An image capture device (130) captures (620) images of photoluminescence simultaneously induced by the substantially uniform, simultaneous illumination incident across the large area for the indirect bandgap semiconductor structure. The photoluminescence images are image processed (622) to quantify spatially resolved specified electronic properties of the indirect bandgap semiconductor structure (140) using the spatial variation of the photoluminescence induced in the large area.
A method is disclosed whereby luminescence images are captured from as-cut or partially processed bandgap materials such as multicrystalline silicon wafers. These images are then processed to provide information about defects such as dislocations within the bandgap material. The resultant information is then utilized to predict various key parameters of a solar cell manufactured from the bandgap material, such as open circuit voltage and short circuit current. The information may also be utilized to apply a classification to the bandgap material. The methods can also be used to adjust or assess the effect of additional processing steps, such as annealing, intended to reduce the density of defects in the bandgap materials.
G01N 21/63 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
H01L 21/66 - Testing or measuring during manufacture or treatment
H01L 31/18 - Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
Methods are presented for separating the effects of background doping density and effective minority carrier lifetime on photoluminescence (PL) generated from semiconductor materials. In one embodiment the background doping density is measured by another technique, enabling PL measurements to be analyzed in terms of effective minority carrier lifetime. In another embodiment the effective lifetime is measured by another technique, enabling PL measurements to be analyzed in terms of background doping density. In another embodiment, the effect of background doping density is removed by calculating intensity ratios of two PL measurements obtained in different spectral regions, or generated by different excitation wavelengths. The methods are particularly useful for bulk samples such as bricks or ingots of silicon, where information can be obtained over a much wider range of bulk lifetime values than is possible with thin, surface-limited samples such as silicon wafers. The methods may find application in solar cell manufacturing.
Embodiments of methods and systems for identifying or determining spatially resolved properties in indirect bandgap semiconductor devices such as solar cells are described. In one embodiment, spatially resolved properties of an indirect bandgap semiconductor device are determined by externally exciting the indirect bandgap semiconductor device to cause the indirect bandgap semiconductor device to emit luminescence (110), capturing images of luminescence emitted from the indirect bandgap semiconductor device in response to the external excitation (120), and determining spatially resolved properties of the indirect bandgap semiconductor device based on a comparison of relative intensities of regions in one or more of the luminescence images (130).
G01N 21/66 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
G01N 21/956 - Inspecting patterns on the surface of objects
Methods and systems are presented for analysing semiconductor materials as they progress along a production line, using photoluminescence images acquired using line- scanning techniques. The photoluminescence images can be analysed to obtain spatially resolved information on one or more properties of said material, such as lateral charge carrier transport, defects and the presence of cracks. In one preferred embodiment the methods and systems are used to obtain series resistance images of silicon photovoltaic cells without making electrical contact with the sample cell.
Methods and systems are presented for analysing samples of a semiconductor material, such as silicon wafers useful for manufacturing photovoltaic cells, for the purpose of assigning grades to the samples, and optionally sorting them into quality bins. The samples are subjected to a photoluminescence-based analysis and at least one non-photoluminescence-based analysis, and the data processed to obtain information on one or more sample properties. The samples are then graded, and optionally sorted, based on these one or more properties. In preferred embodiments the grades are indicative of the performance of photovoltaic cells to be manufactured from the samples.
H01L 21/66 - Testing or measuring during manufacture or treatment
B07C 5/34 - Sorting according to other particular properties
H01L 31/18 - Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
G01N 21/63 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
15.
In-line photoluminescence imaging of semiconductor devices
Methods and systems are presented for acquiring photoluminescence images (2) of silicon solar cells and wafers (4) as they progress along a manufacturing line (36). In preferred embodiments the images are acquired while maintaining motion of the samples. In certain embodiments photoluminescence is generated with short pulse, high intensity excitation, (8) for instance by a flash lamp (50) while in other embodiments images are acquired in line scanning fashion. The photoluminescence images can be analysed to obtain information on average or spatially resolved values of one or more sample properties such as minority carrier diffusion length, minority carrier lifetime, dislocation defects, impurities and shunts, or information on the incidence or growth of cracks in a sample.
Photoluminescence-based methods are presented for facilitating alignment of wafers during metallisation in the manufacture of photovoltaic cells with selective emitter structures, and in particular for visualising the selective emitter structure prior to metallisation. In preferred forms the method is performed in-line, with each wafer inspected after formation of the selective emitter structure to identify its location or orientation. The information gained can also be used to reject defective wafers from the process line or to identify a systematic fault or inaccuracy with the process used to form the patterned emitter structure. Each wafer can additionally be inspected via photoluminescence imaging after metallisation, to determine whether the metal contacts have been correctly positioned on the selective emitter structure. The information gained after metallisation can also be used to provide feedback to the upstream process steps.
Luminescence-based methods are disclosed for determining quantitative values for the series resistance across a photovoltaic cell, preferably without making electrical contact to the cell. Luminescence signals are generated by exposing the cell to uniform and patterned illumination with excitation light selected to generate luminescence from the cell, with the illumination patterns preferably produced using one or more filters selected to attenuate the excitation light and transmit the luminescence.
H01L 21/66 - Testing or measuring during manufacture or treatment
G01N 21/63 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
G01N 21/66 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
Methods and systems are presented for detecting crystal defects such as slip lines in substantially monocrystalline semiconductor wafers and ingots using photoluminescence imaging. A sample of a substantially monocrystalline semiconductor such as Cz-grown or cast monocrystalline silicon is illuminated with light suitable for exciting band-to-band luminescence, one or more images of the luminescence acquired, and the images processed to obtain information about the prevalence or location of crystal defects in the sample. The methods are rapid and non-destructive, unlike existing chemical etching/optical imaging techniques, and the information derived can be used by manufacturers of substantially monocrystalline semiconductor ingots or wafers, or manufacturers of photovoltaic cells produced from such materials, to improve the quality of their products.
G01N 21/892 - Investigating the presence of flaws, defects or contamination in moving material, e.g. paper, textiles characterised by the flaw, defect or object feature examined
G01N 21/88 - Investigating the presence of flaws, defects or contamination
H01L 21/66 - Testing or measuring during manufacture or treatment
Methods are presented for improved detection of persistent or systematic defects induced during the manufacture of a product. In particular, the methods are directed to the detection of defects induced systematically in the manufacture of photovoltaic cells and modules. Images from a plurality of said products are acquired, where each image is of substantially the same area on each of said products. The said images are combined to obtain a super-image, thus enhancing the systematic defects and suppressing random features such as variations in material quality. The super- image is processed to identify regions with strong signals or signals that exceed a predetermined threshold; and said regions are identified as being indicative of systematic features in said products. Once a systematic defect is identified, steps can be taken to locate and rectify its cause.
Methods (600) and systems (100) for inspecting an indirect bandgap semiconductor structure (140) are described. A light source (110) generates light (612) suitable for inducing photoluminescence in the indirect bandgap semiconductor structure (140). A short-pass filter unit (114) reduces long-wavelength light of the generated light above a specified emission peak. A collimator (112) collimates (616) the light. A large area of the indirect bandgap semiconductor structure (140) is substantially uniformly and simultaneously illuminated (618) with the collimated, short-pass filtered light. An image capture device (130) captures (620) images of photoluminescence simultaneously induced by the substantially uniform, simultaneous illumination incident across the large area for the indirect bandgap semiconductor structure. The photoluminescence images are image processed (622) to quantify spatially resolved specified electronic properties of the indirect bandgap semiconductor structure (140) using the spatial variation of the photoluminescence induced in the large area.
Photoluminescence-based methods and systems are presented for monitoring laser processing steps in the manufacture of solar cells. The methods and systems can be used for process control purposes (e.g. adjusting a parameter of the laser exposure) or for quality control purposes (e.g. rejection of defective samples). In certain embodiments photoluminescence imaging is performed during or after a laser processing step to gauge the extent of defects induced by the laser exposure, while in other embodiments photoluminescence imaging is performed before a laser processing step to direct or adjust the subsequent laser exposure. The methods and systems of the invention can be used for example in an R&D environment to optimise a laser processing step, or in-line for real time process control or quality control of a laser processing step in a solar cell manufacture line. Laser processing in solar cell manufacture may for example be used for edge isolation or selective emitter formation.
H01L 21/67 - Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereofApparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components
Disclosed is a method (300) of manufacturing at least one semiconductor photovoltaic cell or module and for classifying semiconductor material. In one implementation (500) the method involves luminescence imaging a wafer at each of a plurality of stages (312-324) of the manufacturing process, and comparing at least two images obtained from the imaging step in respect of the same wafer to identify the incidence or growth of a manufacturing process induced fault. The wafer is removed (351-356) from the manufacturing process (310) where a process induced fault is identified that exceeds a predetermined level of acceptability or the fault may be remedied, or the wafer passed to an alternate manufacturing process to match its characteristics. In an alternate implementation the method comprises classifying semiconductor material. For example, providing at least two wafers, obtaining luminescence images of each wafer comparing the images to determine the electrical structure similarity of the wafers, and grouping wafers with a predetermined level of electrical structure similarity into the same family. The inventive method is suitable for determining various forms of mechanical, electrical and cosmetic irregularities.
Methods are presented for analysing semiconductor materials (8), and silicon photovoltaic cells and cell precursors in particular, using imaging of photoluminescence (12) generated with high intensity illumination (16). The high photoluminescence signal levels (16) obtained with such illumination (30) enable the acquisition of images from moving samples with minimal blurring. Certain material defects of interest to semiconductor device manufacturers, especially cracks, appear sharper under high intensity illumination. In certain embodiments images of photoluminescence generated with high and low intensity illumination are compared to highlight selected material properties or defects.
Methods and systems are presented for acquiring photoluminescence images (2) of silicon solar cells and wafers (4) as they progress along a manufacturing line (36). In preferred embodiments the images are acquired while maintaining motion of the samples. In certain embodiments photoluminescence is generated with short pulse, high intensity excitation, (8) for instance by a flash lamp (50) while in other embodiments images are acquired in line scanning fashion. The photoluminescence images can be analysed to obtain information on average or spatially resolved values of one or more sample properties such as minority carrier diffusion length, minority carrier lifetime, dislocation defects, impurities and shunts, or information on the incidence or growth of cracks in a sample.
A method of photoluminence (PL) imaging of a series of silicon wafers, the method including the step of: utilizing incident illumination of a wavelength greater than 808nm. The present invention further provides a method of analysing silicon semiconductor material utilising various illumination, camera and filter combinations. In some embodiments the PL response is captured by a MOSIR camera. In another embodiment a camera is used to capture the entire PL response and a long pass filter is applied to block a portion of the signal reaching the camera/detector.
Methods and systems are disclosed whereby light scattered laterally within a semiconductor sample is imaged to detect a discontinuity such as a crack. The light can be introduced into the sample using an external light source, or generated in situ as long wavelength photoluminescence. The methods are described with respect to crack detection in silicon wafers and photovoltaic cells, but are applicable in principle to any semiconductor wafer or thin film material.
G01N 21/95 - Investigating the presence of flaws, defects or contamination characterised by the material or shape of the object to be examined
G01N 21/892 - Investigating the presence of flaws, defects or contamination in moving material, e.g. paper, textiles characterised by the flaw, defect or object feature examined
H01L 21/66 - Testing or measuring during manufacture or treatment
G01B 11/30 - Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
A method for analysing a multicrystalline silicon wafer is provided which allows an operator to predict or determine a property characteristic of a photovoltaic device produced from a multicrystalline silicon wafer. The method involves obtaining photoluminescence response after surface texturing. Preferably a photoluminescence response is also obtained before surface texturing. These responses which can be captured as images are then compared and analysed to determine a characteristic parameter of the wafer, e.g. light trapping characteristic which can then be used to predict a property of the photovoltaic device made from the wafer e.g. short circuit current density.
H01L 21/66 - Testing or measuring during manufacture or treatment
G01N 21/63 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
28.
SEPARATION OF DOPING DENSITY AND MINORITY CARRIER LIFETIME IN PHOTOLUMINESCENCE MEASUREMENTS ON SEMICONDUCTOR MATERIALS
Methods are presented for separating the effects of background doping density and effective minority carrier lifetime on photoluminescence (PL) generated from semiconductor materials. In one embodiment the background doping density is measured by another technique, enabling PL measurements to be analysed in terms of effective minority carrier lifetime. In another embodiment the effective lifetime is measured by another technique, enabling PL measurements to be analysed in terms of background doping density. In yet another embodiment, the effect of background doping density is removed by calculating intensity ratios of two PL measurements obtained in different spectral regions, or generated by different excitation wavelengths. The methods are particularly useful for bulk samples such as bricks or ingots of silicon, where information can be obtained over a much wider range of bulk lifetime values than is possible with thin, surface-limited samples such as silicon wafers. The methods may find application in solar cell manufacturing for improving the manufacture of silicon ingots and bricks, or for providing a cutting guide for wafering.
H01L 35/18 - Selection of the material for the legs of the junction using inorganic compositions comprising arsenic or antimony or bismuth
G01N 21/66 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
G01N 21/95 - Investigating the presence of flaws, defects or contamination characterised by the material or shape of the object to be examined
H01L 21/66 - Testing or measuring during manufacture or treatment
29.
MATERIAL OR DEVICE CHARACTERISATION WITH NON-HOMOGENEOUS PHOTOEXCITATION
A method and apparatus for characterising a semiconductor material. The method involves a non-homogeneous illumination (1) to a semiconductor material (2). The material can be a block or wafer of semiconductor material such as silicone, a partially or fully processed solar cell with or without an emitter layer (11). The non- homogeneous illumination (1) provides a first portion subjected to a first predetermined illumination level and a second portion subjected to a second predetermined illumination level less than the first illumination level. The first predetermined illumination level is sufficient to produce a response, eg photoluminescent response in at least the first portion. The method involves acquiring an image of that response and processing the image to determine one or more spatially resolved characteristics of the material. The method is useful in solar cell manufacturing for quality control, process control and process monitoring.
G01N 21/63 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
G01N 21/88 - Investigating the presence of flaws, defects or contamination
G01N 21/66 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
H01L 21/66 - Testing or measuring during manufacture or treatment
Methods are presented for determining an indicator of shunt resistance of a solar cell or a solar cell precursor. The methods involve applying at least one low intensity illumination to the cell or precursor to produce photoluminescence, detecting a resulting level of the photoluminescence, and calculating from the level of detected photoluminescence the likely level of shunt resistance of the solar cell. Preferred methods are applicable to in-line measurement of samples during solar cell manufacture, enabling a number of corrective or remedial actions to be taken. Methods are also presented for monitoring edge isolation processes in solar cell manufacture. Lock-in techniques can be employed to filter noise from the photoluminescence signal.
Methods and apparatus are presented for monitoring the deposition and/or post-deposition processing of semiconductor thin films using photoluminescence imaging. The photoluminescence images are analysed to determine one or more properties of the semiconductor film, and variations thereof across the film. These properties are-used to infer information about the deposition process, which can then be used to adjust the deposition process conditions and the conditions of subsequent processing steps. The methods and apparatus have particular application to thin film-based solar cells.
A method for measuring the spatially resolved series resistance of a photovoltaic device using luminescence imaging. The method involves the steps of measuring a first luminescence intensity of an area of said device utilising an initial illumination intensity and terminal voltage, measuring a second luminescence intensity of said area of said device utilising a varied illumination intensity or varied terminal voltage, and measuring a third luminescence intensity of sai area in which at least one parameter is varied compared to measuring of said second luminescence intensity, said parameters being the terminal voltage and the illumination intensity. The second and third luminescence intensity values are extrapolated or interpolated to determine the values of terminal voltage and illumination intensity that would produce said First luminescence intensity, wherein the determined values are used to estimate the series resistance of said area of the device.
A method (1) is disclosed whereby luminescence images are captured (2) from as-cut or partially processed bandgap materials such as multicrystalline silicon wafers. These images are then processed (3) to provide information about defects such as dislocations within the bandgap material. The resultant information is then utilised (4) to predict various key parameters of a solar cell manufactured from the bandgap material, such as open circuit voltage and short circuit current. The information may also be utilised to apply a classification to the bandgap material. The methods can also be used to adjust or assess the effect of additional processing steps, such as annealing, intended to reduce the density of defects in the bandgap materials.
H01L 31/18 - Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
G01N 21/66 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
34.
Method and system for testing indirect bandgap semiconductor devices using luminescence imaging
Embodiments of methods and systems for identifying or determining spatially resolved properties in indirect bandgap semiconductor devices such as solar cells are described. In one embodiment, spatially resolved properties of an indirect bandgap semiconductor device are determined by externally exciting the indirect bandgap semiconductor device to cause the indirect bandgap semiconductor device to emit luminescence (110), capturing images of luminescence emitted from the indirect bandgap semiconductor device in response to the external excitation (120), and determining spatially resolved properties of the indirect bandgap semiconductor device based on a comparison of relative intensities of regions in one or more of the luminescence images (130).
Disclosed is a method (300) of manufacturing at least one semiconductor photovoltaic cell or module and for classifying semiconductor material. In one implementation (500) the method involves luminescence imaging a wafer at each of a plurality of stages (312- 324) of the manufacturing process, and comparing at least two images obtained from the imaging step in respect of the same wafer to identify the incidence or growth of a manufacturing process induced fault. The wafer is removed (351-356) from the manufacturing process (310) where a process induced fault is identified that exceeds a predetermined level of acceptability or the fault may be remedied, or the wafer passed to an alternate manufacturing process to match its characteristics. In an alternate implementation the method comprises classifying semiconductor material. For example, providing at least two wafers, obtaining luminescence images of each wafer comparing the images to determine the electrical structure similarity of the wafers, and grouping wafers with a predetermined level of electrical structure similarity into the same family. The inventive method is suitable for determining various forms of mechanical, electrical and cosmetic irregularities.
G01N 21/66 - Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
G01N 21/88 - Investigating the presence of flaws, defects or contamination
36.
METHOD AND SYSTEM FOR TESTING INDIRECT BANDGAP SEMICONDUCTOR DEVICES USING LUMINESCENCE IMAGING
Embodiments of methods and systems for identifying or determining spatially resolved properties in indirect bandgap semiconductor devices such as solar cells are described. In one embodiment, spatially resolved properties of an indirect bandgap semiconductor device are determined by externally exciting the indirect bandgap semiconductor device to cause the indirect bandgap semiconductor device to emit luminescence (110), capturing images of luminescence emitted from the indirect bandgap semiconductor device in response to the external excitation (120), and determining spatially resolved properties of the indirect bandgap semiconductor device based on a comparison of relative intensities of regions in one or more of the luminescence images (130).
Methods (600) and systems (100) for inspecting an indirect bandgap semiconductor structure (140) are described. A light source (110) generates light (612) suitable for inducing photoluminescence in the indirect bandgap semiconductor structure (140). A short-pass filter unit (114) reduces long-wavelength light of the generated light above a specified emission peak. A collimator (112) collimates (616) the light. A large area of the indirect bandgap semiconductor structure (140) is substantially uniformly and simultaneously illuminated (618) with the collimated, short-pass filtered light. An image capture device (130) captures (620) images of photoluminescence simultaneously induced by the substantially uniform, simultaneous illumination incident across the large area of the indirect bandgap semiconductor structure. The photoluminescence images are image processed (622) to quantify spatially resolved specified electronic properties of the indirect bandgap semiconductor structure (140) using the spatial variation of the photoluminescence induced in the large area.
