Abstract
We have observed strong photoluminescence (PL) from a well-defined two-dimensional (2D) Si structure formed on a SIMOX (separation by implanted oxygen) wafer, where the thin ( <5 nm) single crystalline silicon film is sandwiched between SiO2 layers. The PL intensity has a sharp maximum at a Si thickness of about 2 nm, whereas the peak photon energy of the PL spectra (1.65 eV) is almost independent of the Si thickness. These results can be interpreted with a three-region model in which electron-hole pairs are excited in the Si well and luminescence occurs at the upper and lower Si/SiO2 interfaces. Furthermore, temperature dependence of PL intensity in the present 2D system is found to be different from previously reported dependence in 0D or 1D Si structures.