Bi doping modulating structure and phase-change properties of GeTe nanowires

Abstract

Bi-doped GeTe nanowires were fabricated using chemical vapor deposition. Composition and microstructure characterizations indicated that Bi (∼3 at. %) doping preserved GeTe rhombohedral structure with slight X-ray diffraction peak shifts, implying material parameters variation. A doping model was proposed where three Bi atoms replaced the middle adjacent Ge sites of (001) plane, accompanied by two adjacent Ge vacancies right over Bi atoms. Ab initio calculations re-validated cell parameters change. Furthermore, Bi-doping process resulted in crystalline and amorphous state resistances increased by ∼2 orders, while a crystallization time dramatically reduced down to 50 μs, 20 times shorter compared to undoped nanowires.