Molecular Beam Epitaxy and Magnetotransport of InBi and InNBi Crystals for High Spin-Orbit Interaction

Bismuth-containing compounds have gained traction in recent years due to the high spin-orbit coupling and bandgap bowing effects of the Bi atom. Bi is a heavy group V element in the same table as N, P, As, and Sb and has been incorporated in dilute amounts in InGaAs and InGaSb. However, there have been few reports of MBE-grown III-Bi binary or III-Nitride-Bi ternary alloys. Here we report the growth of InBi and InNBi films using molecular beam epitaxy. InBi is grown on high-resistivity Si(111) substrates at low temperatures due to the low eutectic point of the indium-bismuth system. By growing significantly thick films in a Bi-rich regime, we obtain coalesced films. Temperature-dependent Hall effect transport and resistivity measurements were performed on these films. We observe a change in the Hall-effect sign from positive to negative due to the change in majority carrier type of Bi-rich InBi and Bi films as temperature decreases. A sign change in the room temperature majority carrier type also appears with increasing indium content in InBi. We additionally discuss the methods used to incorporate Bi into InNBi films grown on GaN/SiC substrates with hopes of introducing high spin-orbit coupling into the GaN material system, where it is nearly absent due to the light N atoms.