First observation of a two-dimensional electron gas at the interface of α-Sn/InSb(100) grown by molecular beam epitaxy

The authors report the first observation of a high-mobility two-dimensional electron gas (2DEG) at the interface of alpha -Sn thin films heteroepitaxially grown on InSb(100) by MBE. Two-dimensionality of the electron gas was demonstrated by the Fourier analysis of the longitudinal and transverse Shubnikov-de Haas (SDH) measurements. The total carrier concentration of the 2DEG is about 6*10 12 cm -2 and at least seven subbands are occupied at 4.2 K. Possible reasons for the occurrence of a 2DEG at this novel polar/non-polar interface between narrow-gap materials of high dielectric constants are discussed in the context of band-offsets at the interface, interfacial charges and other possibilities such as cross-doping and substrate cleaning artefacts.