Due to their excellent properties, ternary GaAsxSb1−x nanowires have been extensively investigated to enable various nanodevice structures. However, the surfactant effect of antimony has a notorious impact on the surface morphology and electrical properties of prepared Sb-rich nanowires, restricting their practical utilization. Herein, through the in situ passivation effect of thiourea, highly-crystalline, uniform, and thin GaAsxSb1−x nanowires (x ≤ 0.34) are successfully achieved. In contrast to low-melting-point sulfur powders typically used in surfactant-assisted chemical vapor deposition, thiourea has a relatively higher melting point, facilitating the more controllable formation of SbxSy layer on the nanowire surface to minimize the radial growth and to stabilize the sidewalls for high-quality Sb-rich nanowires. When configured into field-effect transistors, the obtained GaSb nanowires exhibit excellent device performance with a hole mobility of over 200 cm2 V−1 s−1. The optimal GaAs0.18Sb0.82 device yields an impressive responsivity of 5.4 × 104 A W−1 and an external quantum efficiency of 4.4 × 106% under near-infrared light illumination. Importantly, the rise and decay times are as efficient as 80 and 104 µs, respectively, which are better than any values reported for GaAsSb nanowire photoconductors to date. All these results demonstrate the promising potential of GaAsxSb1−x nanowires for high-mobility electronics and ultrafast near-infrared optoelectronics.
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