Finite Silicon Atom Diffusion Induced Size Limitation on Self-Assembled Silicon Quantum Dots in Silicon-Rich Silicon Carbide

Abstract

Finite Si atom diffusion induced size limitation of self-assembled Si quantum dots (Si-QDs) in silicon-rich silicon carbide (SiC) is demonstrated. After annealing, the Si-QDs with a size of 3 ± 1 nm are precipitated in the matrix of SiC0.51 deposited by low-temperature plasma-enhanced chemical vapor deposition with Argon-diluted silane and methane mixture. The amorphous-Si dependent Raman scattering peak at ∼470 cm−1 is narrowing with increasing temperature, and the Si-CH3 rocking-mode absorption line is shifted by dehydrogenation after high-temperature treatment. The self-assembled Si-QDs in SiC0.51 with a volume density of 4.4 × 1018 cm−3 transfer from amorphous to crystalline phase by increasing annealing temperature from 850°C to 1050°C. The calculated Si atom diffusion coefficient of 3-4 × 10−4 nm2 s−1 in Si-rich SiC0.51 is 7 orders of magnitude larger than that in pure SiC, which coincides with the linear extrapolation from pure Si and SiC and reveals nonlinear proportionality with C/Si composition ratio and Si-QD size.