Reactive ion etched, self-aligned, selective area poly-Si/SiO2 passivated contacts

Front/back poly-Si/SiO2 contact devices suffer from low short-circuit current density, Jsc, due to parasitic optical absorption in the front poly-Si layer. Thin poly-Si (~20 nm) allows for high Jsc but is not compatible with screen-printed fire-through contacts. We therefore study the effects of post-deposition etching of a thick poly-Si (200 nm) front layer by reactive ion etching (RIE) using the metal grid lines as a self-aligned mask. We show that passivation is maintained in the device during RIE and that Jsc is increased by a gain in the blue quantum efficiency response. However, our specific etching parameters cause non-uniform etching of the poly-Si leading to premature loss of passivation without optimal gain in Jsc. Etched, unpassivated layers can be re-passivated with a H-containing dielectric layer leading to a gain in Jsc, open circuit voltage,Voc, Fill-Factor, FF, and efficiency.

David L. Young and Kejun Chen and San Theingi and Vincenzo LaSalvia and David Diercks and Harvey Guthrey and William Nemeth and Matthew Page and Pauls Stradins

Solar Energy Materials and Solar Cells

Ohmic contacts,Passivation,Photovoltaic cells,Poly-Si contacts,Reactive ion etching,Silicon devices

2020

11

10.1016/j.solmat.2020.110621

09270248

110621

Elsevier B.V.

217