Interfacial studies and electrical characterisation of heteroepitaxial InSb on GaAs (100) grown by MBE

Abstract

The growth by molecular beam epitaxy of InSb layers (0.5 < t < 10 μm) on undoped GaAs (100) substrates has been undertaken. In situ reflection high energy electron diffraction and Auger electron spectroscopy have been used to investigate the initial stages of InSb layer nucleation. The GaAs/InSb interface has also been investigated ex vacuo using transmission electron microscopy and secondary ion mass spectrometry. The data reveal a maximum interface width of 25 nm and indicate that the large mismatch (14.6% at room temperature) is accommodated by a network of misfit dislocations at the epilayer substrate interface. Nevertheless, transmission electron microscopy studies and data obtained from double crystal X-ray rocking curves show that the structural quality of the heteroepitaxial InSb improves considerably with increasing layer thickness. The electrical and morphological properties of the InSb heteroepitaxial layers have also been assessed using 77 K Hall, 2 K photoluminescence and Nomarski optical interference microscopy. All layers grown have exhibited p-type carrier concentrations (p ∽ 2 x 10 15 cm -3), a value somewhat higher than observed for the corresponding homoepitaxial material.