Transport spectroscopy from Hubbard bands of dopant-induced quantum dot array to one-dimensional conduction subband

Abstract

Arrays of dopant-induced quantum dots are a promising candidate as the quantum bit platform. We have achieved the quantum transport spectroscopy of a junctionless silicon (Si) nanowire transistor (JNT) with dual physical channels of diameter 10 nm fabricated by novel femtosecond laser projection exposure together with thermal oxidation. The spectroscopy demonstrates the evolution of the quantum transport process from Hubbard bands of dopant-induced quantum dot (QD) array to one-dimensional (1D) conduction subbands. Eight pairs of current splitting peaks were observed at the initial stage of the drain current, representing the upper and lower Hubbard bands formed by the coupling of eight QDs. The current oscillation peaks in the 1D conduction subband elucidate the interference of reflected electron waves between the gate-defined barriers, which are proved by the mean wave vector interval matching the gate length. Our experimental results demonstrate the evolution of the quantum transport process in sub-10-nm dual Si channels with randomly doped dopant atoms, opening a new perspective for quantum states by dopant band engineering in Si nanoscale devices for scalable quantum computation.