Study of intrinsic defects in 3C-SiC using first-principles calculation with a hybrid functional

Abstract

Density functional theory (DFT) with a tailored Hartree-Fock hybrid functional, which can overcome the band gap problem arising in conventional DFT and gives a valence band width comparable with experiment, is applied to determine formation energies and electronic structures of intrinsic defects in cubic silicon carbide (3C-SiC). Systematic comparison of defect formation energies obtained with the tailored hybrid functional and a conventional DFT functional clearly demonstrates that conventional DFT results are not satisfactory. The understanding on intrinsic defects, which were previously investigated mainly with conventional DFT functionals, is largely revised with regard to formation energies, electronic structures and transition levels. It is found that conventional DFT functionals basically lead to (i) underestimation of the formation energy when the defect charge is more negative and (ii) overestimation when the defect charge is more positive. The underestimation is mainly attributed to the well-known band gap problem. The overestimation is attributed to shrinkage of the valence bands, although in some cases such band shrinkage may lead to underestimation depending on how the defect alters the valence band structure. Both the band gap problem and the valence band shrinkage are often observed in semiconductors, including SiC, with conventional DFT functionals, and thus need to be carefully dealt with to achieve reliable computational results.

Native point defects and carbon clusters in 4H-SiC: A hybrid functional study

“…For studies using the Hyde-Scuseria-Ernzerhof (HSE06) hybrid functional, [29][30][31] which reproduces the experimental bandgap of SiC well, defect properties for single vacancies (VSi and VC) [32][33] and vacancy pairs (VSi-VC) 33) were reported in 3C- 33) and 4H-SiC [32][33] , and those for single interstitials (Sii and Ci) and vacancy-type defects including a vacancy-antisite pair (VC-CSi) were investigated in 3C-SiC. 34) However, a systematic study of native point defects including antisites and interstitials in 4H-SiC using the HSE06 hybrid functional is still lacking.…”

Modeling of long-term defect evolution in heavy-ion irradiated 3C-SiC: Mechanism for thermal annealing and influences of spatial correlation

“…27 According to previous DFT studies 17,43 and a recent DFT calculation with a hybrid functional, 59 the stable charge states for point defects are neutral except for the negatively charged V Si , for n-type doping 3C-SiC. To account for V Si , in our model, we assume that V Si will not cluster with each other during OKMC simulation due to the short-range electrostatic repulsion.…”

Dangling bond defects in SiC: An ab initio study

“…30 Previously, similar hybrid functionals for SiC accurately reproduced band gaps and other properties. 18,28,31,32 Computational resource restrictions prevent us from using HYB calculations for 500 SiC unit supercells. However, our HYB calculations, for 108 SiC unit supercells, are compared directly to the respective PBE results and a HYB correction term is established.…”

“…Electronic-structure calculations have confirmed experiments and provided information regarding the vacancy electrical levels. 12,13,18 Recent ab initio calculations identified intrinsic defects in 3C-SiC observed by photoluminescence. 19 Amorphous materials have gained interest due to the use of amorphous SiC alloys in silicon-based integrated-circuit technology.…”