Rear Passivation and Point Contacts Formation by Laser Process through Stacks of a-Si:H(i) and a-Si:B/Sb for High Efficiency Silicon Solar Cell

In this work we investigate the effectiveness of deposited, boron- (for p-type) or antimony-doped (for n-type), amorphous silicon (a-Si:B/Sb) layers for producing multi-purpose films capable of providing both excellent surface passivation and effective localized doping via laser irradiation. We deposit, via sputtering or via a combination of PECVD and sputtering, layers of a-Si:B/Sb or stacks of a-Si:H(i) and a-Si:B/Sb on crystalline silicon substrates, and subsequently employ a KrF 248 nm nanosecond laser to simultaneously remove the film and dope the sub-surface region beneath the film. Sheet resistance measurements indicate that a high level of doping is achieved in laser processed regions for quite a broad range of laser parameters and dopant fractions in deposited films, with sheet resistance as low as around 10 Ω/□ being observed. Furthermore, we evaluate and investigate the passivation capabilities of the films in non-laser processed regions and also determine the recombination properties of the locally laser doped ‘contact’ regions, thus providing an indication of the efficiency potential of PERL type cells utilising these multi-purpose films with laser-doped local contacts