Topological Insulator Sb₂Te₃ and Phase Change Material GeTe Nanowires Synthesis and their Electrical Properties Measurements

Sub-100nm topological insulating(TI) Sb2Te3 nanowires(NWs) and phase change material GeTe nanowires were fabricated by Catalytic Chemical Vaporized Deposition(CVD). The Vapor-Liquid-Solid(VLS) growth mechanism in the fabrication process effectively decreased the growth temperature to around 400°C from around 600-800°C. The stoichiometry ratios of Sb2Te3 NWs(2:3) and GeTe NWs(1:1) had been measured by energy-dispersive X-ray Spectroscopy(EDX) analysis along the NW samples. For the electron spin transports in TI, Magnetic Tunnel Junction contacts at 4K showed a sharp conductance change of non-local magnetoresistance at ±0.5kG, indicates the spin momentum locking effect of topological insulator. P-type conduction property of Sb2Te3 nanowire¹ was measured by the field effect transistor(FET) measurement at 68K with back gate voltage up to 100V across 300nm SiO2 dielectric layer. Phase change property of GeTe nanowire was tested for crystalline and amorphous transition by applying 3V to 5V voltage few hundred ns width voltage pulses, the crystalline form had a resistance at about few kilo-ohm and the amorphous form was at about 30k ohm to 1M ohm range. Preliminary results showed 10 to 20 cycles of switching with no degradation.

1. Arango, Y. C. et al., Sci. Rep. 6, 29493, 2016