Electrical properties of plasma-free ultra-low-temperature ALD ZnS passivation on p-type HgCdTe

Abstract

ZnS thin films have been successfully deposited using metal organic compound with ultra-low-temperature atomic layer deposition (ULT-ALD) at 80 °C. This plasma-free ULT-ALD eliminates the damage to the HgCdTe surfaces due to plasma and high temperature. The capacitance–voltage characteristics of metal–insulator–semiconductor (MIS) structures based on HgCdTe with traditional CdTe/ZnS and ULT-ALD ZnS passivation are studied. The fixed charge surface density at the interface of MIS structures passivated by ALD ZnS was −6.40 × 1011 cm−2, Lower than the value of double-layer passivation 4.20 × 1012 cm−2, and the density of slow states is 5.94 × 1011 cm−3 and 2.61 × 1012 cm−3 respectively. The hysteresis of the MIS structure with ALD ZnS passivation is almost unchanged with temperature. From these findings, combined with characteristics of high density and conformality of ALD films, we conclude that ALD ZnS has better electrical properties than traditional double layer passivation provides significantly improved interface quality, but obtained density of fixed charge is still quite high and should be further reduced.