Electron-tunneling operation of single-donor-atom transistors at elevated temperatures

Abstract

Individual dopant atoms in silicon devices gain active roles as channel dimensions move into the nanoscale. A single donor can work as an atomic quantum dot, mediating single-electron-tunneling transport from source to drain. However, the tunneling operation of single-donor transistors has so far been reported only at low temperatures below \ensuremath{\sim}15 K, while at high temperatures tunneling features are expected to be smeared out. For a higher-temperature single-electron-tunneling operation, the donor's tunnel barriers must be considerably higher than ${k}_{\mathrm{B}}T$. Here, we use a special design of a nanoscale Si channel with a central stub region, in which a phosphorus donor's ground state becomes deeper due to the dielectric confinement effect. In these stub-channel devices, electron tunneling via one donor atom survives even at temperatures above 100 K. Results of ab initio atomistic simulations provide further insights into the fundamental properties of individual donors in ultrasmall nanopatterned structures.