Formation of one-dimensionally self-aligned Si-QDs and their local electron discharging properties

Abstract

Self-aligned Si-quantum-dots (Si-QDs) with an areal density as high as ~1011 cm-2 have been fabricated on ultrathin SiO2 by using a ~4.5 nm-thick poly-Si on insulator (SOI) substrate, and controlling low-pressure chemical-vapor-deposition (LPCVD) using monosilane (SiH4), and followed by thermal oxidation. By controlling the thermal oxidation processes of Si-QDs and the poly-Si layer, we have successfully demonstrated the vertical alignment of Si-QDs, where the Si-QDs are also used as a shadow mask of the underlying poly-Si layer. We also demonstrated in-plane alignment of the one-dimensionally self-aligned Si-QDs on line-patterned SiO2. In addition, from surface potential measurements by using atomic force microscopy (AFM)/Kelvin probe force microscopy (KFM), we confirmed that the initial surface potential change caused by valence electron extraction from the dots to the tip was stably maintained until ~120 min, implying the quantum confinement effect at discrete energy levels of the upper- and lower- QDs.