Laser etch back process to fabricate highly efficient selective emitter c-Si solar cells

Abstract

We developed a novel cost effective process scheme for the fabrication of highly efficient selective emitter solar cells, which uses a laser doping method combined with an etch back process. The laser doping process using a 150 ns pulse width green (532 nm) laser effectively controls the doping profiles to form a selective emitter. However, laser damage was created on the laser-doped surface and eventually the performances and stabilities of laser-doped cells were degraded due to this damage. Using a transmission electron microscope (TEM), the damage was examined and found to have a thickness of 40 nm of amorphous silicon. This thin damage layer was effectively removed in an acid mixture solution. The combined process of laser doping and etch back is called the laser etch back process. After removal of this thin damage layer, the cell efficiencies were significantly improved up to 19.17%. (C) 2014 Elsevier Ltd. All rights reserved.