Size effect on electronic transport in nC–Si/SiOx core/shell quantum dots

Abstract

Electronic transport in silicon quantum dots (Si-QDs) in core/shell configuration was studied. The nC–Si cores encapsulated by protective SiOx shells embedded in a-Si matrix were obtained from one-step and spontaneous plasma processing, at low substrate temperature (300°C) compatible for device fabrication. The size, density and distribution of nC–Si QDs were controlled by optimizing the plasma parameters. Very high electrical conductivity, σ∼4×10−2Scm−1, was achieved at a total number density of Si-QDs, N∼4.8×1011cm−2, corresponding to the lowering in its average core size, d∼3.7nm, to the order of the bulk Si exciton Bohr radius and the associated quantum confinement effects. The electrical conductivity was demonstrated to exhibit quantum size (3<d (nm)<10) effect in zero dimensional quantum dots. The underlying electronic transport was explained using heteroquantum-dot model, the nC–SiOx:H QDs possess hetero-junction like band structure in the interface regions, due to their different band gaps.