Major deep levels with the same microstructures observed in n-type 4H–SiC and 6H–SiC

Abstract

Temperature dependent recombination dynamics in InP/ZnS colloidal nanocrystals Appl. Phys. Lett. 101, 091910 (2012) Intrinsic defect in BiNbO4: A density functional theory study J. Appl. Phys. 112, 043706 (2012) The CuInSe2-CuIn3Se5 defect compound interface: Electronic structure and band alignment Appl. Phys. Lett. 101, 062108 (2012) Investigation of deep-level defects in conductive polymer on n-type 4H-and 6H-silicon carbide substrates using I-V and deep level transient spectroscopy techniquesMajor deep levels observed in as-grown and irradiated n-type 4H-SiC and 6H-SiC epilayers have been investigated. After low-energy electron irradiation, by which only carbon atoms are displaced, five traps, EH1 ͑E C − 0.36 eV͒, Z 1 / Z 2 ͑E C − 0.65 eV͒, EH3 ͑E C − 0.79 eV͒, EH5 ͑E C − 1.0 eV͒, and EH6/7 ͑E C − 1.48 eV͒, were detected in 4H-SiC and four traps, E 1 / E 2 ͑E C − 0.45 eV͒, RD 5 ͑E C − 0.57 eV͒, ES ͑E C − 0.80 eV͒, and R ͑E C − 1.25 eV͒, were detected in 6H-SiC. The Z 1 / Z 2 , EH6/7 centers in 4H-SiC and the E 1 / E 2 , R centers in 6H-SiC exhibit common features as follows: their generation rates by the e − -irradiation were almost the same each other, their concentrations were not changed by heat treatments up to 1500°C, and they showed very similar annealing behaviors at elevated temperatures. Furthermore, these defect centers were almost eliminated by thermal oxidation. Taking account of the observed results and the energy positions, the authors suggest that the Z 1 / Z 2 center in 4H-SiC corresponds to the E 1 / E 2 center in 6H-SiC, and the EH6/7 center in 4H-SiC to the R center in 6H-SiC, respectively. Since the concentrations of these four centers are almost the same for as-grown, electron-irradiated, annealed, and oxidized samples, these centers will contain a common intrinsic defect, most likely carbon vacancy. The authors also observed similar correspondence for other thermally unstable traps in 4H-SiC and 6H-SiC.

Annealing behavior of the EB-centers and M-center in low-energy electron irradiated n-type 4H-SiC

“…One sample was further annealed in a sublimation reactor at 1600 C. Only slightly reduced signatures of Z 1=2 or EH6/7 are left in the DLTS spectrum as previously reported by several authors. 16,21,22 The annealing of these two centers takes place at rather high temperatures, T % 2000 C. The annealing of the EB-centers occurs at higher temperatures than for the M-center and the EH1/EH3, which were proposed to be due to the recombination of mobile carbon interstitials but at lower temperatures than the Z 1=2 or EH6/7, which were attributed to the carbon vacancy. The EB-centers are thus likely carbon interstitial related complex defect.…”

“…12 Several studies in different temperature ranges and for different irradiation energies were previously presented. Multistage annealing processes are calculated for Frenkel pairs in irradiated SiC 20 and measured in electron irradiated n-type 4H-SiC; 16 highly movable related defects anneal first before elementary, stable defects start to decrease, e.g., Z 1=2 and EH6/7 above 1700 C. 12,16,21,22 The annealing can be enhanced under injection of carriers due to electron-hole recombination at the defect site, 23 which may change the charge state. 24 The defect migration is thus increased.…”

Deep levels in tungsten doped n-type 3C–SiC

“…The shape of the two peaks is very similar for all polytypes. Sasaki et al 4 recently showed that these levels most probably originate from the same defect, likely the carbon vacancy. They additionally concluded that the LangerHeinrich rule, which was previously only applied for transition metals, is valid also for intrinsic defects in SiC.…”

“…Most investigations were conducted on the 4H-SiC polytype and only recently, a comparative study on defects in 4H-SiC and 6H-SiC and their behavior after oxidation has revealed common characteristics on the origin of these intrinsic defects. 4 Previously, defect studies on 3C-SiC bulk material 5 and cubic layers grown on Si have been done. [6][7][8][9] However, due to the heteroepitaxial growth, it has not been clear, which of the defects are related to the interface and which that are related to 3C-SiC.…”

Capacitance transient study of a bistable deep level in e−-irradiated n-type 4H–SiC

“…It is known, that the valence bands of the different SiC-polytypes [31] align and previously it was observed, that also intrinsic defects align [29,32]. Hemmingsson et al [16] detected a multistable defect present in 6H-SiC.…”