Simulation and Optimization of Silicon Solar Cell Back Surface Field

Abstract

In this paper, TCAD Silvaco (Technology Computer Aided Design) software has been used to study the Back Surface Field (BSF) effect of a p+ silicon layer for a n+pp+ silicon solar cell. To study this effect, the J-V characteristics and the external quantum efficiency (EQE) are simulated under AM 1.5 illumination for two types of cells. The first solar cell is without BSF (n+p structure) while the second one is with BSF (n+pp+ structure). The creation of the BSF on the rear face of the cell results in efficiency  of up to 16.06% with a short-circuit current density Jsc = 30.54 mA/cm2, an open-circuit voltage Voc = 0.631 V, a fill factor FF = 0.832 and a clear improvement of the spectral response obtained in the long wavelengths range. An electric field and a barrier of potential are created by the BSF and located at the junction p+/p with a maximum of 5800 V/cm and 0.15 V, respectively. The optimization of the BSF layer shows that the cell performance improves with the p+ thickness between 0.35 – 0.39 μm, the p+ doping dose is about 2 × 1014 cm-2, the maximum efficiency up to 16.19 %. The cell efficiency is more sensitive to the value of the back surface recombination velocity above a value of 103 cm/s in n+p than n+pp+ solar cell.