A Method for Imaging the Emitter Saturation Current With Lateral Resolution

A method is developed to measure the emitter saturation current density J_0e 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 J_0e 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 J_0e images of selective emitter test structures are discussed, including measurement uncertainties. The J_0e 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.