Programmable Nucleation and Growth of Ultrathin Tellurium Nanowires via a Pulsed Physical Vapor Deposition Design

Abstract

Physical vapor deposition (PVD) methods have been widely employed for high-quality crystal growth and thin-film deposition in semiconductor electronics. However, the fabrication of emerging low dimensional nanostructures is hitherto challenging in conventional PVD systems due to their large thermal mass and near-continuous operation which hinder flexible control of the nucleation and growth events. Herein, a pulsed PVD method is reported that features finely controllable temperature and heating time (down to milliseconds), which enables programming of the vapor supersaturation and decoupling of nucleation and growth events. Take tellurium as an example, the pulsed PVD allows transient source vaporization (≈1000 °C, 30 ms) for burst nucleation, followed by relatively low-temperature volatilization (≈600 °C, 5 min) for steady-state growth with well-suppressed random nucleation. As a result, uniform and high-density tellurium nanowires are obtained at the ultrathin thickness of sub-10 nm and length >10 µm, which is in sharp contrast to the randomly formed nanostructures in conventional PVD. When used in the field-effect transistor, the thin tellurium nanowires display a high on-off ratio of >104 and hole mobility of ≈40 cm2 V−1 s−1, showing the potential for high-performance electronics. Pulsed PVD therefore enables to flexibly program and finely tailor the nucleation and growth events during vapor phase deposition, which are otherwise impossible in conventional PVD.