Thermal stability of single layer pulsed — DC reactive sputtered AlOX film and stack of ICP ℄ CVD SiNX on AlOX for p-type c-Si surface passivation

Abstract

High thermal stability is a requirement for thin films explored for solar cell applications. In this paper the thermal stability of single layer AlO_X film deposited by pulsed - DC (p-DC) reactive sputter technique and a stack of AlO_X/SiN_X for surface passivation of p - type crystalline silicon (c-Si) is compared. The SiN_X film of thickness of 70 nm, was deposited using inductively coupled plasma (ICP) - CVD technique. The single layer AlO_X shows an effective surface recombination velocity (S_eff) of approximately 44 cm. s^-1 after annealing in an optimized condition, while the stack shows a relatively poor S_eff of 624 cm. s^-1 on p-type c-Si surface. The degradation of surface passivation by stack can be related to the decrease in number of total negative fixed oxide charges (Q_f) from 6.5×10¹² to 1.8×10¹² cm^-2, that leads to a decrease in field - effect passivation. Also the thermal stability of both were compared in terms of surface passivation for temperatures upto 700 °C, and no change in thermal stability is observed with the capping of the AlO_X by SiN_X film.