Photoluminescence of Ge quantum dots prepared on porous silicon by ultrahigh vacuum chemical vapor deposition

Abstract

This letter reports a way of preparing Ge quantum dots on anodized porous silicon layers by ultrahigh vacuum chemical vapor deposition at a low temperature of 720 °C. The porous silicon was formed by anodic conversion of p-type (100) oriented crystalline silicon in hydrofluoric acid diluted by alcohol. A clear phonon-resolved photoluminescence (PL), as a no-phonon (NP) and its transverse acoustic phonon replica, was observed from the Ge dots at the temperature of 10 K. The blueshift energy is as high as about 136 meV, but the full width at half maximum of the NP PL spectrum is only 1.23 meV. We attributed the very large blueshift in energy of the PL peak to quantum size confinement effect of the Ge quantum dots.