Assessing the effect of H on the electronic properties of 4H-SiC

As a common impurity in 4H-silicon carbide (4H-SiC), hydrogen (H) may play a role in the tuning of the electronic properties of 4H-SiC. In this work, we systemically explore the effect of H on the electronic properties of both n-type and p-type 4H-SiC. The passivation of H for intrinsic defects such as carbon vacancies (VC) and silicon vacancies (VSi) in 4H-SiC is also evaluated. We find that interstitial H at the bonding center of the Si-C bond (Hi bc) and interstitial H at the tetrahedral center of Si (Hi Si-te) dominate the defect configurations of H in p-type and n-type 4H-SiC, respectively. For n-type 4H-SiC, the compensation of Hi Si-te is found to pin the Fermi energy and hinder the increase of electron concentration for highly N-doped 4H-SiC. The compensation of Hi bc is negligible compared to that of VC on the p-type doping of Al-doped 4H-SiC. We have further examined whether H can passivate VC and improve carrier lifetime in 4H-SiC. It turns out that nonequilibrium passivation of VC by H is effective to eliminate the defect states of VC, which enhances the carrier lifetime of moderately doped 4H-SiC. Regarding the quantum-qubit applications of 4H-SiC, we find that H can readily passivate VSi during the creation of VSi centers. Thermal annealing is needed to decompose the resulting VSi-nH (n=1~4) complexes and promote the uniformity of the photoluminescence of VSi arrays in 4H-SiC. The current work may inspire the further development of the impurity engineering of H in 4H-SiC.