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

Abstract

We report first-principles calculations that clarify the formation energies and charge transition levels of native point defects and carbon clusters in the 4H polytype of silicon carbide (4H-SiC) under a carbon-rich condition. We applied a hybrid functional that reproduces the experimental bandgap of SiC well and offers reliable defect properties. For point defects, we investigated single vacancies, antisites, and interstitials of Si and C on relevant sites. For carbon clusters, we systematically introduced two additional C atoms into the perfect 4H-SiC lattice with and without removing Si atoms and performed structural optimization to identify stable defect configurations. We found that neutral Si antisites are energetically favorable among Si-point defects in a wide range of the Fermi level position around the intrinsic regime, whereas negatively-charged Si vacancies and a positively-charged Si interstitial on a site surrounded by three Si and three C atoms become favorable under nand p-type conditions, respectively. For C-point defects, neutral C antisites are favorable under intrinsic and n-type conditions, whereas positively-charged C vacancies become favorable under p-type conditions.We also found that a di-carbon antisite is more favorable than a C-split interstitial, which is the most stable form of single C interstitials.2

Formation of carbon interstitial-related defect levels by thermal injection of carbon into n-type 4H-SiC

“…41 did not calculate CTLs of the single C i in 4H-SiC to compare with those of di-interstitials. Kobayashi et al have used hybridfunctional DFT calculations to predict the formation energies and CTLs of various native point defects and clusters in 4H-SiC 22 . They find the (0/−) CTL of the carbon split mono-interstitial C i,split in its k and h configurations at E C − 0.7 eV and E C − 0.33 eV.…”

Photoluminescence line shapes for color centers in silicon carbide from density functional theory calculations

“…Si ) positioned at both h and k sites, and the doubly negative charge state (V −2 Si ) at the k site [23,49]. Regarding divacancies (V C V Si ), we study configurations comprising a Si vacancy on an h site in combination with C vacancies on either h or k sites.…”

“…Electronic structure calculations can be extremely useful to obtain detailed insight and understanding of defects, at a level inaccessible to experiment. Accordingly, they have been routinely used to analyze, e.g., charge transition levels, spin states, and ZPLs [22,23,28,[48][49][50]. It was, however, only very recently [24,25] that the PSBs of V Si were calculated and compared to experimental data.…”

Carbon dangling-bond center (carbon Pb center) at 4H-SiC(0001)/SiO2 interface

“…They include either a P bC center (a DB on a C adatom) or a P b center (a Si DB formed at the surface). The lattice parameters of SiC were fixed to the values obtained in our previous calculations, 30,31 and the defect structures were relaxed using the Perdew-Burke-Ernzerhof functional 32 until the remaining forces were less than 40 meV/Å . Note that, by calculating the formation energies of 114 types of mono-and di-carbon defects in 4H-SiC(0001)/SiO 2 systems, we found that the C adatom shown in Fig.…”

“…2(a) appears as one of the metastable forms of carbon-related defects. 30,31 Next, we check the HF constants of the P bC center, which was performed using the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional. [34][35][36] The contribution of core states (A 1c ) 36 is included in the calculation of HF constants.…”