Effect of H2-dilution in Si-cap formation on photoluminescence intensity of Si quantum dots with Ge core

We have fabricated high-density Si quantum dots (QDs) with Ge core on SiO₂ by controlling the thermal decomposition of pure SiH₄ and GeH₄ alternately for the selective growth of a Ge core and a Si cap on pre-grown Si-QDs, and studied the effect of H₂ dilution of SiH₄ for Si cap formation on their photoluminescence (PL) properties. PL from the Si-QDs with Ge core observed at room temperature in an energy region from 0.68 to 0.85 eV irrespective of H₂ concentration for the Si cap formation. However, with increasing the H₂ concentration, the intensity of PL originating from radiative recombination between the first-third quantized states in the Si-QDs with Ge core was increased. The results will lead to the development of high efficient light-emitting devices using Si-based QDs.