Solar Energy Materials and Solar Cells, Vol.106, 80-83, 2012
p-type c-Si solar cells based on rear side laser processing of Al2O3/SiCx stacks
In this work, we further investigate a new strategy to passivate and contact the rear side of p-type c-Si solar cells based on the laser processing of aluminum oxide (Al2O3)/amorphous silicon carbide (SiCx) stacks before rear metallization. For this stack, surface passivation of outstanding quality is obtained with effective surface recombination velocities in the 1 cm/s range on < 100 > FZ 2.3 Omega cm p-type substrates. The dielectric stack is processed with a 1064 nm laser defining square matrixes of spots where the dielectric film is opened. Simultaneously, part of the aluminum contained in the Al2O3 film is locally introduced into the c-Si, creating a p+ region. The presence of a SiCx capping layer onto the Al2O3 helps in the formation of this local back surface field reducing surface recombination velocity at the contacts to similar to 2 x 10(3) cm/s. This new technique is applied to 2 x 2 cm(2) solar cells leading to photovoltaic conversion efficiencies well beyond 20% on 0.5 and 2.3 Omega cm substrates. (C) 2012 Elsevier B.V. All rights reserved.
Keywords:Silicon solar cells;Laser-fired contacts;Aluminum oxide;Silicon carbide;Surface passivation;Back surface field