Analysis of carrier smearing and evaluation of its influence in luminescence imaging
Nekane Azkona, Federico Recart, Pedro Rodriguez, Vanesa Fano, Aloņa Otaegi, Juan Carlos Jimeno
Institute of Microelectronic Technology - UPV/EHU, Bilbao, Spain

The use of luminescence, and particularly photoluminescence imaging (PLI) as characterization technique is nowadays normalized both in industry and in laboratory scale. The main reasons are the possibility of acquiring a whole map of the carrier product, in any type of sample from wafer to the finish cell (provided is not completely metallized) and in contactless mode (fast and harmless). Anyway, the interpretation of this n·p product to obtain lifetime related values has been kind of an approximation sometimes, as lateral carrier diffusion has not always been taken into account. As the measurement methods improve, the effort is dedicated to get a better resolution. The main target is the correction of the blurring effect, related to the use of CCD cameras as detection method; and obviating carrier smearing or even erroneously assigning one effect to the other. In this work we explain the effect of carrier mobility in a wafer and in a pn junction, and quantify its impact in the luminescence based measurements.

Area: Sub-Area 5.5: Advanced Characterization of Photovoltaic Devices