Characterization of electron charging and transport properties of Si-QDs with phosphorus doped Ge core

Abstract

We formed high-density Si quantum dots (Si-QDs) with undoped and P-doped Ge cores on thermally-grown SiO 2 by controlling low pressure chemical vapor depositions of Si and Ge. Doping into the Ge core was carried out during selective-growth of Ge on pre-grown Si-QDs. From hard x-ray photoelectron spectroscopy measurements, we confirmed phosphorus incorporation into the Ge core, where phosphorus donor concentration in the Ge core was roughly estimated to be ∼0.09 at%. When the surfaces of Si-QDs with undoped and P-doped Ge cores were scanned with an Rh-coated tip biased at 0 V, the surface potential of Si-QDs with P-doped Ge cores were increased by ∼30 mV, while that of Si-QDs with undoped Ge cores remained unchanged. These results indicate that an electron was extracted from the conduction band of the Ge core due to a phosphorus donor. In the current images measured with the Rhcoated tip, the current level of Si-QDs with P-doped Ge cores on n-Si(100) substrates was higher than that of Si-QDs with undoped Ge cores. This result indicates that phosphorus donor can contribute to an increase in the electron injection rate from the Si-substrate.

Characterization of Light Emission Properties of Impurity Doped Ge/Si Core–Shell Quantum Dots

“…We have also confirmed no significant size change in the Ge core with and without P-or B-doping. Phosphorus and Boron activations into the Ge cores were also confirmed from surface potential changes measured before and after bias application by means of an AFM/Kelvin probe technique using a Rh-coated AFM cantilever (not shown) [18,19]. Under 976-nm light excitation of the Si-QDs with and impurity δ-doped ~3.3 nm Ge core using a semiconductor laser, stable PL signals in the energy region from 0.62 to 0.85 eV were detected at room temperature, as shown in Fig.…”