Achieving a low interfacial density of states in atomic layer deposited Al2O3 on In0.53Ga0.47As

Abstract

Atomic-layer-deposited ${\text{Al}}_2{\text{O}}_3$ on ${\text{In}}_{0.53}{\text{Ga}}_{0.47}\text{As}$ with short air exposure between the oxide and semiconductor deposition has enabled the demonstration of nearly ideal frequency-dependent and quasistatic capacitance-voltage $\left(C\text{-}V\right)$ characteristics. The excellent quasistatic $C\text{-}V$ characteristics indicate a high efficiency of 63% for the Fermi-level movement near the midgap. A low mean interfacial density of states $\left({\overline{D}}_{\text{it}}\right)\sim 2.5\times {10}^{11}{\text{cm}}^{-2}{\text{eV}}^{-1}$ was determined under 1 MHz using a charge pumping method, which was also employed to probe the depth profile of bulk traps $\left(N_{\text{bt}}\right)$ and the energy dependence of $D_{\text{it}}$ at 50 kHz: a low $N_{\text{bt}}\sim 7\times {10}^{18}{\text{cm}}^{-3}$ and a $D_{\text{it}}$ of $\left(2–4\right)\times {10}^{11}{\text{cm}}^{-2}{\text{eV}}^{-1}$ in the lower half of the band gap and a higher $D_{\text{it}}$ of $\sim {10}^{12}{\text{cm}}^{-2}{\text{eV}}^{-1}$ in the upper half of the band gap. The employment of charge pumping method has given a more accurate determination of $D_{\text{it}}$ , which is usually overestimated using other commonly methods such as the Terman, conductance, and high-low frequencies due to the influence of weak inversion at room temperature.