Numerical modelling of silicon p+ emitters passivated by a PECVD AlOx/SiNx stack

Abstract

Extraction of the exact surface recombination velocity at highly doped crystalline silicon (c-Si) surfaces is not straightforward and typically involves advanced computer modelling. In this work, two theoretical methods (the Kane-Swanson slope method and the general definition) for the extraction of the emitter saturation current density J0e are compared in SENTAURUS TCAD. We find good agreement between the J0e values obtained by the two methods. Experimental p+ emitter doping profiles on planar {100} samples are used to calibrate the process simulation, followed by a calculation of the doping profiles for textured {111} samples featuring upright pyramids. The experimentally measured J0e values of both textured and planar samples passivated by PECVD AlOx/SiNx stacks are reproduced by adjusting the surface recombination velocity. The electron surface recombination velocity parameter Sn0 at the p+ c-Si/AlOx interface is determined to be ∼1 104 cm/s for all investigated p+ emitters on planar wafers, comparable to values reported for lightly doped c-Si. A high density of fixed charge is found to reduce J0e by up to 90%, due to the suppression of Shockley-Read-Hall recombination at the surface. © 2013 Published by Elsevier Ltd. Selection.