T.A.G. Eberlein

Shallow acceptors in GaN

Recent high resolution photoluminescence studies of high quality Mg doped GaN show the presence of two acceptors. One is due to Mg and the other labeled A1 has a shallower acceptor defect. The auth ...

Electrical and optical properties of rod-like defects in silicon

Self-interstitials in silicon can aggregate to form rod-like defects (RLDs) having both electrical and optical activity. We carry out local density functional calculations for both {113} and {111} RLDs to determine their structures and electrical activity. We find that small {113} RLDs are more stable than {111} RLDs but this reverses for larger defects. We attribute the electrical activity of {113} RLDs found in deep level transient spectroscopy studies with the bounding dislocations and the 0.903 eV photoluminescence to vacancy point defects lying on the habit plane.

Planar interstitial aggregates in Si

Self-interstitials in silicon aggregate to form rod-like defects aligned along [110] directions and inhabiting either {111} or {113} crystallographic planes. These systems are known to be electrically and optically active. We present the results of first-principles calculations on the structure and energetics for candidate structures contained within the {113}, {111} and {001} planes and compare the results with experiment.

Self-interstitial clusters in silicon

Abstract Although there have been made many calculations for structures of the self-interstitial in Si and small aggregates of interstitials, I n , there have been relatively few attempts to relate these defects with experimental data. Here, we discuss the assignments of the self-interstitial to the AA12 EPR centre and the di-interstitial to the P6 EPR centre.

Effect of charge on the movement of dislocations in SiC

SiC bipolar devices show a degradation under forward-biased operation which has been linked with a current induced motion of one of the two glide dislocations having either Si or C core atoms. We have carried out calculations of the core structures and dynamics of partial dislocations in 3C and 2H–SiC. In this work we present results on the effect of charge on the dislocation kinks. The calculations show that silicon kinks have a deep filled band above the valence band and the trapping of holes into this band permits motion at room temperature.

Hydrogen molecules in 4H-SiC and 2H-GaN

We present the results of theoretical calculations of the structure, diffusion and rotational energies, and the ro-vibrational modes, of the hydrogen molecule in the hexagonal part of 4H-SiC and in 2H-GaN. In both materials, the molecule is stable and aligned along the c-axis. Its rotational barrier is sufficiently large that ortho- and para-forms have almost degenerate ro-vibrational modes. The origin of two modes at 4090 and 4110 cm−1 attributed to molecules observed in multi-transmission FTIR experiments on Mg doped insulating GaN grown by OMVPE is discussed.

Theory of Dislocations in SiC: The Effect of Charge on Kink Migration

Under forward bias bipolar 4H- and 6H-SiC devices are known to degrade rapidly through stacking fault formation and expansion in the basal plane. It is believed that the ob- served rapid stacking fault growth is due to a recombination-enhanced dislocation glide (REDG) mechanism at the bordering partial dislocations. This degradation phenomenon has generated considerable interest in the involved dislocations — in particular in their atomic and electronic structure, but also in the mechanisms of their glide motion. Fortunately, nowadays advances in computing power and in theoretical methodology allow the ab initio based modelling of some aspects of the problem. This paper therefore gives a brief review of recent activities in this field, and further discusses some general problems of ab initio based modelling of dislocations in compound semiconductors.