EPR, ESE, and pulsed ENDOR study of the nitrogen donors in 15R SiC grown under carbon‐rich conditions

Abstract

X‐band field‐sweep electron spin echo and pulsed electron nuclear double resonance (ENDOR) spectroscopy were used to study n‐type 15R SiC wafers grown under carbon (C)‐rich conditions with the aim to verify the recently proposed concept that nitrogen (N) donors substitute both carbon (C) and silicon (Si) sites and may occupy nonequivalent positions at Si sites. It was found that besides the 14N ENDOR spectra of the C substituting quasicubic “k1”, “k2”, and “k3” positions five doublet lines due to 14N nuclei at other lattice positions were observed in the ENDOR spectrum of highly compensated C‐rich n‐type 15R SiC. Three of them with the hyperfine interaction (HFI) constants 34.66, 32.20, and 29.77 MHz were attributed to the N donors substituting “k1”, “k2”, and “k3” positions at Si sites. Two other additional ENDOR spectra were explained by the presence of the C antisite (CSi) defects in C‐rich 15R SiC, which leads to the formation of CSiNC complexes with donor levels close to the conduction‐band minimum and isotropic 14N HFI constants of 21.58 and 25.94 MHz. The energy levels of N donors have been evaluated by comparing the number of ENDOR spectra observed in C‐rich 15R SiC with different degrees of compensation.

Temperature dependent behavior of localized and delocalized electrons in nitrogen-doped 6H SiC crystals as studied by electron spin resonance

“…A great amount of effort has been devoted to the investigation of nitrogen (N) donors in silicon carbide (SiC) polytypes by magnetic resonance methods. [1][2][3][4][5][6][7][8][9] However, the electron spin resonance (ESR) properties of N in n-type SiC with low and intermediate donor concentration (N D -N A ) varying from 210 16 to 710 17 cm -3 have so far been extensively studied at low temperatures when the donor electrons are bound in the ground state of the donor atoms. In this case, the ESR spectrum consists of two triplet lines due to the hyperfine (hf) interaction with 14 N nuclei (I = 1, 99.6%) corresponding to N donors at quasi-cubic "k1" and "k2" sites (N k1,k2 ), a line with a small unresolved hf splitting due to the N substituting hexagonal ("h") position (N h ) and a line triplet N x with S = 1 due to the distant donor pairs formed between the N atoms residing at quasi-cubic and hexagonal sites.…”

Magnetic Resonance Study of p‐Type 3C SiC Microparticles

“…It is well known that electron paramagnetic resonance (EPR) is a powerful technique to study the electronic structure of donors and acceptors in SiC polytypes. [3][4][5][6][7][8][9][10][11][12][13][14] It was recently reported that triplet EPR lines due to the isolated N donor state corresponding to the N donor center substituting quasicubic position with the deep energy level in the bandgap at 142 meV are observed in the SiC nanoparticles with grain size d > 100 nm. [15] With a decrease in the particle size up to 50 nm, the N line triplet transforms into one single exchange line due to the delocalization of the donor wave function caused by the size confinement effect.…”

“…It is well known that electron paramagnetic resonance (EPR) is a powerful technique to study the electronic structure of donors and acceptors in SiC polytypes. [ 3–14 ]…”