Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H–SiC

Abstract

Electrically active induced energy levels in semiconductor devices could be beneficial to the discovery of an enhanced p or n-type semiconductor. Nitrogen (N) implanted into 4H-SiC is a high energy process that produced high defect concentrations which could be removed during dopant activation annealing. On the other hand, boron (B) substituted for silicon in SiC causes a reduction in the number of defects. This scenario leads to a decrease in the dielectric properties and induced deep donor and shallow acceptor levels. Complexes formed by the N, such as the nitrogen-vacancy centre, have been reported to play a significant role in the application of quantum bits. In this paper, results of charge states thermodynamic transition level of the N and B vacancy-complexes in 4H-SiC are presented. We explore complexes where substitutional N[Formula: see text]/N[Formula: see text] or B[Formula: see text]/B[Formula: see text] sits near a Si (V[Formula: see text]) or C (V[Formula: see text]) vacancy to form vacancy-complexes (N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text] and B[Formula: see text]V[Formula: see text]). The energies of formation of the N related vacancy-complexes showed the N[Formula: see text]V[Formula: see text] to be energetically stable close to the valence band maximum in its double positive charge state. The N[Formula: see text]V[Formula: see text] is more energetically stable in the double negative charge state close to the conduction band minimum. The N[Formula: see text]V[Formula: see text] on the other hand, induced double donor level and the N[Formula: see text]V[Formula: see text] induced a double acceptor level. For B related complexes, the B[Formula: see text]V[Formula: see text] and B[Formula: see text]V[Formula: see text] were energetically stable in their single positive charge state close to the valence band maximum. As the Fermi energy is varied across the band gap, the neutral and single negative charge states of the B[Formula: see text]V[Formula: see text] become more stable at different energy levels. B and N related complexes exhibited charge state controlled metastability behaviour.

Defect levels induced by double substitution of B and N in 4H-SiC

“…The geometric structure of 4H-SiC supercell shows that the relaxed Si-C bond distance is 1.89 Å, which is in agreement with previous results [30,31]. role in determining the energy of formation since a system that experienced more strain is likely to form with a relatively higher formation energy than a system that experienced less strain in the bond length by the participating atoms.…”

“…The criteria for calculating the chemical potential for the B, N, C and Si atoms and their values where taken from Ref. [30].…”

Induced defect levels of P and Al vacancy-complexes in 4H-SiC: A hybrid functional study

“…The chemical potentials µ Si for Si, µ C for C, µ P for P and µ Al for Al should satisfy the stability condition for bulk SiC. The µ, the effective chemical potential of the constituent of the compound must satisfy the condition µ ≤ H f , where H f (0.62 eV from our calculation [26]) is the heat of formation. In a perfect stoichiometry growth, µ must be equal to zero.…”

“…Several experimental [5,6,7,8,9,10,11,12,13,14,15,16,17] and theoretical [18,19,20,21,22] (most especially using the well known density functional theory) studies of point defects in 4H-SiC have been reported. Point defects such as substitution, interstitials, vacancy and defect-complexes (interstitial-complex, vacancy-complex or antisite) have been reported in literature [18,19,23,24,25,26]. Report on the nuclear transmutation proceeding under high energy doping of Si and SiC by P suggests that an n-type phosphorus doped layer induced radiation damage defects in SiC [27].…”

“…The supercell atomic positions were relaxed using the same convergence criteria as of the unit cell but with a reduced 2 × 2 × 2 Monkhorst-Pack k-point grid. More information about the convergence criteria of the supercell canbe found in our previous report[26]. Inside the supercell, a P atom was substituted at either C or S atomic site and a C or Si vacancy was created to form a P related vacancy-complex.…”