Photoluminescence Study of Si Quantum Dots with Ge Core

Abstract

Si quantum dots (Si-QDs) with doped Ge core were self-assembled on thermally grown SiO2 from alternate thermal decomposition of pure SiH4 and GeH4 diluted with He. When the sample was excited by a 979 nm line of semiconductor laser, photoluminescence (PL) spectra peaked at ~0.70 eV were observed, even at room temperature. The observed PL band suggested that radiative recombination of photo-generated carriers through quantized states of the Ge core is the dominant pathway for the emission from the dots, reflecting the type II energy band discontinuity between the Si clad and Ge core. We also found that, for P-delta doping to the Ge core, an ionized P donor is responsible for the efficient PL from the P-doped Ge core Si-QDs.