Effects of external stress on defect complexes in semiconductors
Crystal field gradients that exist at lattice sites in solids depend on the symmetry of charge distribution around atomic sites. The charge symmetry could be broken either by the presence of impurity complexes in the host matrix or by external stress on the samples, which leads to an observable magnitude of electric field gradients (EFGs). The perturbed γ–γ angular correlation (PAC) method is employed here to investigate the effect of uniaxial stress on 111Cd sites in crystalline doped semiconductors.
Acceptor-donor pairs in germanium
The formation of acceptor-donor pairs in germanium was studied by perturbed angular correlation spectroscopy. At the single acceptor In the donors P and As were trapped, resulting in In-P and In-As pairs as well as in In-P2 complexes. At the double acceptor Cd three P and two As correlated configurations were formed, i.e. Cd-P and Cd-As pairs, Cd-P2, Cd-As2 and Cd-P3 complexes. In Ge:Sb and Ge:Se the pairing of Cd acceptors with Sb or Se donors was detected. As predicted by calculations of the Coulomb binding energy the stability of the complexes decreases with increasing number of involved donor atoms, and a configuration formed at the double acceptor Cd reveals a higher stability than the analogous one at the single acceptor In. The weak temperature dependence of the corresponding field gradients indicates either electrical inactivity of Cd-donor complexes or the generation of shallow levels.
On the mixed group III and group V implantations in silicon and germanium
Abstract A simple explanation of the mixed group III and group V implantation in silicon and germanium, based on the local chemical bond, is proposed. In particular, the charge states of the Frenkel defects and their role in the reaction kinetics are discussed in detail.