Study of electron transport characteristics through self-aligned Si-based quantum dots

Self-aligned Si-based quantum dots (QDs) with an ultra-thin oxide interlayer were spontaneously formed on ∼1.0-nm-thick thermally grown SiO2/Si(100) by a process sequence that consists of Si-QDs formation by controlling low-pressure chemical vapor deposition (LPCVD) using pure Si2H6, selective Ge-LPCVD, thermal oxidation of the dots, thermal desorption of Ge oxide, and subsequent formation of the Si-QDs. After formation of Al back electrode, electron transport properties through the aligned dots structures so-prepared were characterized by employing atomic force microscopy with a conductive cantilever. The tunneling current through the aligned dots exhibited a clear current bump and negative differential conductance at room temperature with a peak current to valley ratio as high as 100 at around the resonance voltage as a result of resonant tunneling mediated by the quantized energy levels of the dots.