Combined effect of (NH<inf>4</inf>)<inf>2</inf>S<inf>x</inf> treatment and post-metallization annealing with plasma-enhanced chemical vapour deposition silicon nitride gate dielectric on the GaAs metal-insulator-semiconductor characteristics and the photoluminescence characteristics of GaAs substrates

In this paper we present a GaAs surface passivation technique using (NH4)2Sx treatment and plasma-enhanced chemical vapour deposition silicon nitride. The passivation effects are demonstrated by the improvement in the capacitance-voltage (C-V) and the photoluminescence (PL) data. Post-metallization annealing (PMA) at 450°C is required to obtain a good 1 MHz C-V curve and high band-edge PL intensities. Even though higher-temperature PMA shows better values of C-V and lower interface state density (Dit), it reduces the band-edge PL intensities. This is attributed to the hydrogen incorporation into GaAs during higher-temperature annealing cycles.