Characterization of photoluminescence from Si quantum dots with B δ-doped Ge core

Abstract

We formed undoped and B-doped Si quantum dots (Si-QDs) with Ge core on thermally-grown SiO2 by controlling the low pressure chemical vapor depositions for the pre-growth of Si-QDs, and the selective growth of Ge cores and Si-caps. Boron atoms were doped by the pulse injection of 1% B2H6 diluted with He of 1–5 times during the selective growth of Ge cores. When the surfaces of undoped and B-doped Si-QDs with Ge core were scanned with an Rh-coated tip biased at 0 V, the surface potential of the Si-QDs with B-doped Ge core were decreased by around -20 mV, while that of the Si-QDs with undoped Ge core remained unchanged. These results can be interpreted in terms that electrons were injected into the valence band of the Ge cores with holes supplied from boron acceptors, suggesting that boron atoms were activated in the Ge cores. We characterized room temperature photoluminescence (PL) and found that PL intensity was increased with an increase in B2H6 pulse injection number from 1 to 4, where the integrated PL intensity of a sample with 4 pulse-doping was increased by a factor of 2.4 compared to the undoped dots.