Energetics and kinetics of vacancy defects in 4H-SiC

RK Defo and XY Zhang and D Bracher and G Kim and E Hu and E Kaxiras, PHYSICAL REVIEW B, 98, 104103 (2018).

DOI: 10.1103/PhysRevB.98.104103

Defect engineering in wide-gap semiconductors is important in controlling the performance of single-photon emitter devices. The effective incorporation of defects depends strongly on the ability to control their formation and location, as well as to mitigate attendant damage to the material. In this study, we combine density functional theory, molecular dyamics (MD), and kinetic Monte Carlo (KMC) simulations to study the energetics and kinetics of the silicon monovacancy V-Si and related defects in 4H-SiC. We obtain the defect formation energy for V-Si in various charge states and use MD simulations to model the ion implantation process for creating defects. We also study the effects of high-temperature annealing on defect position and stability using KMC and analytical models. Using a larger (480-atom) supercell than previous studies, we obtain the temperature- dependent diffusivity of V-Si in various charge states and find significantly lower barriers to diffusion than previous estimates. In addition, we examine the recombination with interstitial Si and conversion of V-Si into CSiVC during annealing and propose methods for using strain to reduce changes in defect concentrations. Our results provide guidance for experimental efforts to control the position and density of V-Si defects within devices, helping to realize their potential as solid-state qubits.

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