Controlled Synthesis of Pure-Phase GaAs Nanowires through Shear Tension

The identical crystal phase is one of the most critical and challenging subjects in the fabrication of low dimensional III–V semiconductors for electronic and optoelectronic applications. The polytype boundaries induced by the coexistence of wurtzite (WZ) and zinc blende (ZB) phases in the nanowire (NW) limits the device performance. It is interesting to find that the epitaxially grown GaAsSb shell outside the WZ/ZB mixed-phase GaAs NW will induce the complete transformation of WZ segments of GaAs to ZB structures due to the shear tension. The underlying physical mechanism was proposed and verified by first-principle transition barrier calculations and the Shockley partial dislocations theory. Based on the fabricated pure-phase NW, a proof-of-concept high-performance avalanche photodiode was demonstrated, which shows responsivity and a multiplication factor up to 3.3 × 103 A/W and 8.62 × 103 at −11.5 V, respectively. This work promises shear tension as an effective strategy for the controlled syntheses of single-phase semiconductor NWs and other nanostructures.