Surface passivation of III-V compound semiconductors using atomic-layer-deposition-grown Al2O3

Abstract

${\mathrm{Al}}_2{\mathrm{O}}_3$ was deposited on ${\mathrm{In}}_{0.15}{\mathrm{Ga}}_{0.85}\mathrm{As}∕\mathrm{GaAs}$ using atomic-layer deposition (ALD). Without any surface preparation or postthermal treatment, excellent electrical properties of ${\mathrm{Al}}_2{\mathrm{O}}_3∕\mathrm{InGaAs}∕\mathrm{GaAs}$ heterostructures were obtained, in terms of low electrical leakage current density (${10}^{-8}$ to ${10}^{-9}\mathrm{A}∕{\mathrm{cm}}^2$ ) and low interfacial density of states $\left(D_{it}\right)$ in the range of ${10}^{12}{\mathrm{cm}}^{-2}{\mathrm{eV}}^{-1}$ . The interfacial reaction and structural properties studied by high-resolution x-ray photoelectron spectroscopy (HRXPS) and high-resolution transmission electron microscopy (HRTEM). The depth profile of HRXPS, using synchrotron radiation beam and low-energy ${\mathrm{Ar}}^{+}$ sputtering, exhibited no residual arsenic oxides at interface. The removal of the arsenic oxides from ${\mathrm{Al}}_2{\mathrm{O}}_3∕\mathrm{InGaAs}$ heterostructures during the ALD process ensures the Fermi-level unpinning, which was observed in the capacitance-voltage measurements. The HRTEM shows sharp transition from amorphous oxide to single crystalline semiconductor.