Hydrogen-Plasma Assisted Molecular Beam Epitaxial Growth of High-Purity Inas

In this article we report the effect of H plasma on the purity and transport properties of molecular beam epitaxial (MBE) grown InAs, which has attracted considerable attention for high-speed and low power electronic devices in recent years. We observed that the native oxide on the InAs surface could be desorbed at temperatures as low as 300°C under H-plasma irradiation. The time required for oxide desorption increased with decreasing substrate temperature. Thick InAs was grown with H-plasma assistance on semi-insulating (SI) GaAs and on an AlAs0.16Sb0.84∕InAs insulating buffer layer to investigate the effect of H plasma on the transport properties of InAs. Significant improvement of the electron mobility was observed using H-plasma assisted growth. For 6μm InAs grown with H plasma on SI GaAs, the electron mobilities were as high as 98000cm2∕Vs at 77K and 19500cm2∕Vs at 300K, which represent the best published data for MBE grown InAs on GaAs. For thick InAs grown on AlAs0.16Sb0.84∕InAs, the electron mobilities were as high as 420000cm2∕Vs at 77K and 31000cm2∕Vs at 300K. The free carrier concentration of InAs grown with H-plasma assistance is larger than that of the sample grown without, indicating the H plasma yields a much lower compensation ratio γ(γ=(NA+ND)∕n), and moreover, the H plasma is more effective in passivating acceptors than donors in InAs. The mobility and free carrier concentration were both unchanged after thermal annealing, which are advantageous for device processing.