Gate‐Tunable Hole Transport in In‐Plane Ge Nanowires by V‐Groove Confined Selective Epitaxy

Abstract

Germanium (Ge) nanowires hold great promise as building blocks for hole spin‐based quantum processors. Realizing this potential requires their direct integration onto silicon (Si) wafers. This work introduces V‐groove‐confined selective epitaxy to enable the in‐plane growth of nanowires on Si substrates. Nanowires form fully confined within V‐shaped grooves, a process driven by surface energy minimization and in agreement with Winterbottom‐like construction calculations. This confinement eliminates the direct Ge–SiO₂ interface, reducing spurring charge noise and enhancing nanowire functionality. Aberration‐corrected scanning transmission electron microscopy reveals the cross‐sectional shape and single‐crystalline nature of the nanowires. Low‐temperature magnetotransport measurements on Ge nanowire Hall bars demonstrate gate‐tunable hole densities and a peak mobility of approximately 600  cm² V⁻¹s⁻¹ at a density of 1.2 × 10¹³ cm⁻². These findings establish V‐groove‐confined epitaxy as a scalable pathway for the integration of high‐performance Ge nanowire‐based quantum devices.