Diode Laser-Crystallization for the Formation of Passivating Contacts for Solar Cells

Abstract

A new method of diode laser treatment of passivating contacts for solar cells application based on electron beam evaporated highly doped amorphous silicon (a-Si) layers deposited on solar-grade Czochralski wafers with SiOx tunneling layers is investigated. In a first step, an interface oxide is grown and a highly doped n-type a-Si layer is deposited on both sides by electron beam evaporation. In a next step, the laser treatment is applied. Two different scanning speeds of 15 and 20 mm s−1 are used. Electron backscattering diffraction and quasi-steady-state photo conductance measurements indicate that the a-Si layer can be crystallized without breaking up the thin oxide layer. To determine the best parameters, the lifetime and the implied open-circuit voltage for each laser power are measured. The first results show a fitted lifetime of 4.06 ms and an implied open-circuit voltage up to 711 mV after a passivation step.