Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Methods (200, 300), apparatuses and systems (100) for determining minority carrier diffusion lengths in a semi-conductor structure (130), which may be a solar cell or a unprocessed or partially processed silicon sample, are disclosed. The luminescence (140) may comprise photoluminescence, electroluminescence, or both. Luminescence (140) is excited (212) in the structure (130), and the intensities of short- and long-wavelength luminescence (140) are measured (214). Luminescence intensities may be captured from either side of the sample using a single photodetector, a FPA, a CCD array (150), or a mapping tool. The luminescence (140) excited in the structure (130) may be filtered (160) at short and long cutoff wavelengths. Diffusion lengths of the structure (130) are generated (216) using a predefined theoretical relationship.

Abstract: 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.

Abstract: Methods (200, 300), apparatuses and systems (100) for determining minority carrier diffusion lengths in a semi-conductor structure (130), which may be a solar cell or a unprocessed or partially processed silicon sample, are disclosed. The luminescence (140) may comprise photoluminescence, electroluminescence, or both. Luminescence (140) is excited (212) in the structure (130), and the intensities of short- and long-wavelength luminescence (140) are measured (214). Luminescence intensities may be captured from either side of the sample using a single photodetector, a FPA, a CCD array (150), or a mapping tool. The luminescence (140) excited in the structure (130) may be filtered (160) at short and long cutoff wavelengths. Diffusion lengths of the structure (130) are generated (216) using a predefined theoretical relationship.

Abstract: 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).

Abstract: 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.