Boron-doped Ge-core/Si-shell quantum dots (Si-QDs with Ge core) were self-assembled on thermally-grown SiO2 from the thermal decomposition of alternate pure SiH4 and GeH4 diluted with H2. Changes in the surface potential caused by electron charging to the B-doped Si-QD with Ge core were studied using a Kelvin probe technique in atomic force microscopy. We also demonstrated that the room temperature photoluminescence (PL) intensity increased appreciably with B-doping into the Si shell. The increase in the PL intensity is interpreted in terms of a hole(s) in the Ge core and a negatively-charged ionized B acceptor(s) in the Si shell resulting from electron transfer from the valence band of the Ge core to the B acceptor, which increased the amplitude of the electron wave function penetrating the Ge core from the Si shell to enhance the radiative recombination rate between electrons in the conduction band and holes in the valence band of the Ge core.