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

This letter reports a way of preparing Ge quantum dots on anodized porous s ilicon layers by ultrahigh vacuum chemical vapor deposition at a low temper ature of 720 degreesC. The porous silicon was formed by anodic conversion o f p-type (100) oriented crystalline silicon in hydrofluoric acid diluted by alcohol. A clear phonon-resolved photoluminescence (PL), as a no-phonon (N P) and its transverse acoustic phonon replica, was observed from the Ge dot s 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 qua ntum size confinement effect of the Ge quantum dots. (C) 2001 American Inst itute of Physics.