Orientation controlled GaSb nanowires: From growth to application

In recent years, high-mobility GaSb nanowires have received tremendous attention for high-performance p-type transistors; however, due to the difficulty in achieving thin, uniform and orientation-controlled nanowires (NWs), there is limited report until now addressing their orientation-dependent properties in this important one-dimensional material system, where all these are essential information for the deployment of GaSb NWs in various applications. Using CMOS-compatible Pd catalysts, we demonstrated the formation of high-mobility 〈111〉 -oriented GaSb nanowires (NWs) via vapor-solid-solid (VSS) growth by the newly developed surfactant-assisted chemical vapor deposition through a complementary experimental and theoretical approach. In contrast to NWs formed by the conventional vapor-liquid-solid (VLS) mechanism, cylindrical-shaped Pd ₅ Ga ₄ catalytic seeds were present in our Pd-catalyzed VSS-NWs. As solid catalysts, stoichiometric Pd ₅ Ga ₄ was found to have the lowest crystal surface energy and thus giving rise to a minimal surface diffusion as well as an optimal in-plane interface orientation at the seed/NW interface for efficient epitaxial NW nucleation. Over 95% high crystalline quality NWs were grown in 〈111〉 orientation for a wide diameter range of between 10 and 70 nm. Back-gated field-effect transistors (FETs) fabricated using the Pd-catalyzed GaSb NWs exhibit a superior peak hole mobility of 330 cm ² V ^-1 s ^-1 , close to the mobility limit for a NW channel diameter of 30 nm with a free carrier concentration of 10 ¹⁸ cm ^-3 . This suggests that the NWs have excellent homogeneity in phase purity, growth orientation, surface morphology and electrical characteristics. Contact printing process was also used to fabricate large-scale assembly of Pd-catalyzed GaSb NW parallel arrays, confirming the potential constructions and applications of these high-performance electronic devices.