Group III Acceptors with Shallow and Deep Levels in Silicon Carbide: ESR and ENDOR Studies

Magnetic Resonance Study of p‐Type 3C SiC Microparticles

“…[16][17][18][19][20][21][22] The EPR and electron-nuclear double resonance (ENDOR) spectra of B acceptor with hyperfine interaction with intensively studied by many authors in SiC monocrystals, resulting in a few microscopic models for shallow and deep B centers. [6][7][8][9]13,14,[23][24][25][26] The shallow B EPR spectrum is described by the following spin Hamiltonian…”

“…where μ B is Bohr magneton of the electron, B ¼ (0, 0, B 0 )externally applied magnetic field, g is the electronic g tensor with the principal values: g x , g y , g z , S ¼ 1/2-electron spin, ℏ ¼ h/2π-Plank constant, and A is the hyperfine (hf ) tensor with the principal values: A x , A y , A z , describing the hf interaction of 11 B nuclei with I ¼ 3/2. Following the latest model, [25] shallow B occupies silicon (Si) site, and the main spin density (the hole) is located in a dangling bond of one 13 C-ligand oriented along the B─C bond, forming B Si À Cþ-like configuration, as a result of the Jahn-Teller distortion. Consequently, off-center relaxed B Si has a stronger binding with three of its carbon (C) ligands, which have different bond lengths, and the hybrid orbitals are shifted from sp 3 to three sp 2 hybrid orbitals and one pure p orbital in which unpaired spin is mainly localized.…”

“…[ 16–22 ] The EPR and electron–nuclear double resonance (ENDOR) spectra of B acceptor with hyperfine interaction with 11 B nuclei ( I = 3/2, S = 1/2, natural abundance 80.2%) have been intensively studied by many authors in SiC monocrystals, resulting in a few microscopic models for shallow and deep B centers. [ 6–9,13,14,23–26 ] The shallow B EPR spectrum is described by the following spin Hamiltonianwhere μ B is Bohr magneton of the electron, B = (0, 0, B 0 )— externally applied magnetic field, g is the electronic g tensor with the principal values: g x , g y , g z , S = 1/2—electron spin, ℏ = h /2 π —Plank constant, and A is the hyperfine (hf) tensor with the principal values: A x , A y , A z , describing the hf interaction of 11 B nuclei with I = 3/2.…”

“…Following the latest model, [ 25 ] shallow B occupies silicon (Si) site, and the main spin density (the hole) is located in a dangling bond of one 13 C‐ligand oriented along the BC bond, forming B Si − C+‐like configuration, as a result of the Jahn–Teller distortion. Consequently, off‐center relaxed B Si has a stronger binding with three of its carbon (C) ligands, which have different bond lengths, and the hybrid orbitals are shifted from sp 3 to three sp 2 hybrid orbitals and one pure p orbital in which unpaired spin is mainly localized.…”

“…Recently, the other interpretation of the experimental data was suggested in ref. [25]. Considering small differences between the values of the g ‐tensor for x and y axes, which lie in the plane perpendicular to the z ‐axis, it was suggested that g ‐tensor of shallow B centers is almost axial with respect to the local z ‐axis for all shallow B acceptors in cubic and hexagonal polytypes of SiC at low temperatures.…”