First Principle Characterization of Optical Charge State Conversion of the Carbon Antisite-Vacancy in 4H-SiC

Wide band-gap semiconductors such as Silicone Carbide (SiC) can host color centers with potential for near-infrared optical emissions and spin properties suitable for quantum technologies. Charge state control of such defects is vital, as any change in the charge state can lead to the loss of favorable properties. Charge state transitions can occur due to the optical pumping used to excite the defect and modeling of such events is therefore an important part of color center characterization. In this work, we study the carbon antisite-vacancy pair (C_SiV_C) in 4H-SiC which shows promise for optical transitions at telecom wavelength¹ and is thought to be involved in ultrabright transitions at room temperature². We theoretically characterize this defect, focusing on the optical excitations with charge-state altering capabilities and show that our results can predict thresholds for optical charge transitions. In addition, we calculate relevant hyperfine coupling tensors for all paramagnetic charge states and discuss our results in the light of recent EPR measurements³ demonstrating evidence of optically driven charge state transitions.

¹K. Szász et al., Phys. Rev. B 91, 121201 (2015).
²S. Castelletto et al., Nat. Mater. 13, 151 (2014).
³N. T. Son et al., Appl. Phys. Lett. 114 (2019).