Temperature dependence of deep level positions and capture cross sections in vanadium-doped 4H-SiC

Abstract

4H-SiC has emerged as a crucial semiconductor material for power electronic devices due to its superior physical properties, including high breakdown field, electron saturation drift velocity, and thermal conductivity. Vanadium, an amphoteric transition metal impurity and intra-transition color center in 4H-SiC, plays a vital role through compensation doping to prepare semi-insulating substrates, with applications in microwave power and quantum devices. Using density functional theory with screened hybrid functionals and Heyd, Scuseria, and Ernzerhof + Vw corrections, we investigated temperature-dependent behavior of V acceptor levels and capture cross sections to interpret deep-level transient spectroscopy (DLTS) signals. Our research reveals that at 800 K, the VSi(0/−) transition level decreases by approximately 0.07 eV compared to 0 K, while electron capture cross sections increase by more than 1000 times their room temperature value. Considering the intra-transition excited states of V ions, we predicted additional transition levels and temperature-dependent capture cross sections. The theoretically predicted 0/− and 0∗/−∗ levels align well with two DLTS peaks: E1 at 425 K (corresponding to an activation energy of 0.85 eV) and E2 at 660 K (corresponding to an activation energy of 1.15 eV). We calculated entropy factors from theoretical-apparent capture cross section discrepancies. This research enhances understanding of DLTS results for vanadium impurities in 4H-SiC, helping establish temperature dependence of trap energy levels and Shockley–Read–Hall recombination rates, benefiting high-temperature power device modeling and photoconductive switch simulations under specific conditions.