Area preferential nucleation of Ge nano-dots on nano-size porous silicon

The Ge quantum dots on anodized nanometer porous silicon layers are prepared by area preferential nucleation at a low temperature of 720°C. The porous silicon was formed by anodic conversion of p-type (1 0 0)-oriented crystalline silicon in hydrofluoric acid diluted by alcohol. Clear phonon-resolved PL, as a NP transition and its TA phonon replica, was observed from the Ge dots at the temperature of 10 K. We attributed the very large blue-shift in energy of the PL peak to the quantum size effect in Ge dots. The present technique is a potential low-cost method for producing quantum dot arrays.