Structural and compositional analysis of InBi_xAs_ySb_(1-x-y) films grown on GaAs(0 0 1) substrates by liquid phase epitaxy

Abstract

The growth of epitaxial InBi_xAs_ySb_(1-x-y) layers on highly lattice mis-matched semi-insulating GaAs substrates has been successfully achieved via the traditional liquid phase epitaxy. Orientation and single crystalline nature of the film have been confirmed by X-ray diffraction. Scanning electron micrograph shows abrupt interface at micrometer resolution. Surface composition of Bi(x) and As(y) in the InBi_xAs_ySb_(1-x-y) film was measured using energy dispersive X-ray analysis and found to be 2.5 and 10.5 at.%, respectively, and was further confirmed with X-ray photoelectron spectroscopy. Variation of the composition with depth of the film was studied by removing the layers with low current (20 μA) Ar⁺ etching. It was observed that with successive Ar⁺ etching, In/Sb ratio remained the same, while the As/Sb and Bi/Sb ratios changed slightly with etching time. However after about 5 min etching the As/Sb and Bi/Sb ratios reached constant values. The room temperature band gap of InBi_0.025As_0.105Sb_0.870 was found to be in the range of 0.113-0.120 eV. The measured values of mobility and carrier density at room temperature are 3.1×10⁴ cm² V^-1 s^-1 and 8.07×10¹⁶ cm^-3, respectively.