Deep-Level Defects in Nitrogen-Doped 6H-SiC Grown by PVT Method

Abstract

An effect of the nitrogen concentration on the concentrations of deep-level defects in bulk 6H-SiC single crystals is investigated. Six electron traps labeled as T1A, T1B, T2, T3, T4 and T5 with activation energies of 0.34, 0.40, 0.64, 0.67, 0.69, and 1.53 eV, respectively, were revealed. The traps T1A (0.34 eV) and T1B (0.40 eV), observed in the samples with the nitrogen concentration ranging from ~2x10 17 to 5x10 17 cm -3 , are attributed to complexes formed by carbon vacancies located at various lattice sites and carbon antisites. The concentrations of traps T2 (0.64 eV) and T3 (0.67 eV) have been found to rise from ~5x10 15 to ~1x10 17 cm -3 with increasing the nitrogen concentration from ~2x10 17 to ~2.0x10 18 cm -3 . These traps are assigned to complexes involving silicon vacancies occupying hexagonal and quasi-cubic sites, respectively, and nitrogen atoms. The trap T4 (0.69 eV) concentration also substantially rises with increasing the nitrogen concentration and it is likely to be related to complexes formed by carbon antisites and nitrogen atoms. The midgap trap T5 (1.53 eV) is presumably associated with vanadium contamination. The presented results show that doping with nitrogen involves a significant change in the defect structure of 6H-SiC single crystals.

A new method of calculating charged deep level defects density in doped semiconductors from the band offsets of MIS device interfaces

“…A literature survey of charged defect density calculations provides N id data for three of the six semiconductors in Table I: Si [3], 4H-SiC [4][5], and 6H-SiC [6]. These data match very well to the calculations in the Table and hence the author has the confidence in the theory and method of calculating N id presented in this article.…”

“…In equations (6) and (7), N C is the density of states in the conduction band, N V is the density of states in the valence band, E C is the bottom of the conduction band, E V is the top of the valence band, E F is the Fermi level in a semiconductor, k is the Boltzmann constant, and T is the temperature in Kelvin. Substituting equations (6) and 7for p and n in equation 5gives:…”

Epitaxial Deposition of SiC onto 4H SiC using a Hollow Cathode

“…A common method is that of hot wall chemical vapor deposition (CVD) (2,3). Another, considerably faster method, is physical vapor transport (PVT) (4,5) or sublimation (1). Molecular beam epitaxy (MBE) has also been used, but not much has been reported on MBE of SiC, the literature reveals only solid MBE onto Si (6) and gas source MBE onto SiC (7).…”