Native interstitial defects in ZnGeN2

Abstract

A density functional study is presented of the interstitial Zni, Gei, and Ni in ZnGeN2. Corrections to the band gap are included by means of the LDA+U method. The Zn and Ge interstitials are both found to strongly prefer the larger octahedral site compared to the two types of tetrahedral sites. The Zn interstitial is found to be a shallow double donor but has higher energy than previously studied antisite defects. It has a resonance in the conduction band which is Zn-s like. The Ge interstitial is an even higher energy of formation defect and also behaves as a shallow double donor but has also a deep level in the gap, corresponding to a Ge-s orbital character while the Ge-p forms a resonance in the conduction band. The nitrogen interstitial forms a split-interstitial configuration, as also occurs in GaN. Its electronic levels can be related to that of a N2 molecule. The defect levels in the gap correspond to the πg-like lowest unoccupied molecular orbital (LUMO) of the molecule, which here becomes filled with 3 electrons in the defect's neutral charge state. They are found to prefer a high-spin configuration in the q = +1 state. The corresponding transition levels are obtained and show that this is an amphoteric trap level occurring in +2, +1, 0 and −1 charge states. The two possible sites for this split interstitial, on top of Zn or on top of Ge differ slightly in N2 bond-length. While the Ni defects have the lowest formation energy among the interstitials, it is still higher than that of the antisites. Hence they are not expected to occur in sufficient concentration to affect the intrinsic Fermi level position. In particular, they do not contribute to the unintentional n-type background doping.

First-principles study of point defects in LiGaO2

“…Interstitial defects will be considered in the future but comparison with II-IV-N 2 semiconductors suggest that they would be of high energy. 25,26 The defect energies of formation are shown for the six chemical potential points A, B, C, D, E and F in Fig. 2.…”

Band Gaps, Band‐Offsets, Disorder, Stability Region, and Point Defects in II‐IV‐N2 Semiconductors

“…In the present paper, we first provide a brief literature review, then we present some additional results complementing some of our recent papers and finally discuss the importance of cation disorder on the point defects in one of these materials, ZnGeN 2 . In particular, we use the present paper to compare our results with the recent paper by Adamski et al…”

“…In the present paper, we first provide a brief literature review, then we present some additional results complementing some of our recent papers and finally discuss the importance of cation disorder on the point defects in one of these materials, ZnGeN 2 . In particular, we use the present paper to compare our results [1,2] with the recent paper by Adamski et al [3] N 2 compounds [40][41][42] ; the phonons and related Raman and infrared spectra [43][44][45][46][47][48] ; and the elastic and piezoelectric constants and spontaneous polarizations. [49,50] Very recently we also studied BeGeN 2 and BeSiN 2 's electronic band structure and phonons.…”

“…The point defects in ZnGeN 2 were reported in two of our previous papers, [1,2] the first one addressing vacancies and antisites, while the second one addressed interstitials. Since then, one other study has been reported by Adamski et al [3] Here we compare the results of the two studies and update some of our results in view of the updated chemical potential diagram discussed in the previous section.…”