A Method for Imaging the Emitter Saturation Current With Lateral Resolution

A method is developed to measure the emitter saturation current density
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with lateral resolution. The method uses photoluminescence lifetime imaging at several different injection densities to evaluate the injection-dependent effective excess carrier lifetime, from which
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is derived at each pixel using the method of Kane and Swanson. The applicability of the method is successfully demonstrated on laser-doped selective emitters for crystalline Si solar cells. The derived
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images of selective emitter test structures are discussed, including measurement uncertainties. The
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images may, for example, be used to optimize the laser parameters of selective emitters and to quantify laser damage, and may also provide input parameters for device simulation.