Unusual phase-pure zinc blende and highly-crystalline As-rich InAs_1-xSb_x nanowires for high-mobility transistors 

Due to the excellent electrical and optical properties, small bandgap III-V nanowire (NW) materials hold the great promises for future electronics and optoelectronics. In particular, InAs_1-xSb_x, the ternary alloy of InAs and InSb, is one of the most studied III-V nanomaterial systems; however, the As-rich As-rich InAs_1-xSb_x  nanowires are usually obtained with significant crystal phase mixing and high density of planar defects, limiting their electrical transport characteristics. In this work, unusual phase-pure zinc blende and highly-crystalline As-rich As-rich InAs_1-xSb_x NWs with x<0.2 are successfully achieved by solid-source chemical vapor deposition, where this excellent phase-purity and crystallinity has not been reported elsewhere. By simply controlling the precursor powder mixing ratio between InAs and InSb, the morphology and composition of NWs can be controlled reliably. When these As-rich InAs_1-xSb_x NWs are fabricated into field-effect transistors, they exhibit the superior device performance, especially the high electron mobility. In specific, the average peak mobility of InAs_0.948Sb_0.502 NW device can be improved up to 3160 cm²V−1s⁻¹, which is substantially better than the one of pure InAs NW counterparts (2030 cm²V⁻¹s⁻¹). This mobility enhancement can be attributed to the Sb-alloyed-induced electron effective mass reduction. Also, there exists a surface charge accumulation layer on the NWs as confirmed by the decrease of device transconductance measured under vacuum, indicating future possibilities to manipulate the NW surface for enhanced functionality. All these results evidently indicate the potential of these phase-pure zinc blende As-rich As-rich InAs_1-xSb_x NWs for high-mobility devices.