Base contacts and selective emitters processed by laser doping technique for p-type IBC c-Si solar cells

Abstract

Abstract

In this work, we describe a novel fabrication process of p-type interdigitated back contact (IBC) silicon solar developed by means of laser doping and laser firing techniques. We use dielectric layers both as dopant sources to create highly-doped regions and as passivating layers. In particular, we use phosphorus-doped silicon carbide stacks (a-SiCx (n)) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and aluminum oxide (Al2O3) layer deposited by atomic layer deposition (ALD). Emitters were fabricated with a light thermal phosphorus diffusion in order to reduce bulk and surface emitter recombination losses. Highly doped regions n++ (emitter) and p++ (base) were simultaneously created in a point-like structure using a pulsed Nd-YAG 1064 nm laser in the nanosecond regime by laser processing the dielectric layers. The results obtained for a cell, 3x3 cm2, are presented. Efficiencies up to 18.1% (Jsc = 39 mA/cm2, Voc = 632 mV, FF = 73.4%) have been achieved in our fabricated IBC cells.