Surface-oxide stress induced band-structure modulation in two-dimensional Si layers

摘要

We experimentally studied an impact of the surface oxide layer on quantum confinement effects (QCE) in Si quantum well (SQW) structures (surface-oxide/two-dimensional-Si/ buried-oxide) with various surface oxide layer thickness T-OX on silicon-on-insulator (SOI) substrate, by UV-Raman spectroscopy, photoluminescence (PL) method, and two-dimensional (2D) stress simulator. UV-Raman data show that tensile strain epsilon of SQW, stressed by a thermal expansion mismatch between surface oxide and Si layers, decreases with decreasing the T-OX. According to the strain behavior in the SQW and strained-Si on strained-SOI, PL results show that bandgap E-G of the SQW rapidly expands with decreasing T-OX. As a result, we can estimate the E-G of the fully relaxed SQW. However, QCE in SQW keep thermally stable, in spite of carrying out a high temperature N-2 annealing process. (C) 2015 The Japan Society of Applied Physics