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.
Pairing of acceptors with interstitial donors in silicon and germanium
Abstract The interaction of acceptor atoms with the interstitial impurity atoms hydrogen and lithium in the semiconductors silicon and germanium has been studied with help of the perturbed γγ angular correlation technique at the radioactive acceptor 111 In. The formed acceptor-donor pairs, as characterized by their electric field gradients, show some striking differences in silicon and germanium. In particular, besides the thermal stability of the pairs, the number of formed InLi and InH complexes is different in silicon and germanium. The behaviour of the formed complexes as a function of the carrier concentration will be discussed.
Positron trapping in vacancies in indium doped CdTe crystals
Abstract In weakly n-type CdTe(In) crystals grown by the travelling heater method, positrons annihilate in vacancy-type defects with a lifetime of 320 ± 4 ps. The concentration of these native defects varies with the concentration of indium and electron in agreement with the model of self-compensation where the indium donors are compensated by indium-vacancy complexes. These defects are assumed to be (VCdIn)- complexes. The positron trapping in these complexes disappears at low temperature. This phenomenon is attributed to competing trapping of positrons by negative ions which are either residual impurities or intrinsic defects.