Positron Distribution in Semiconductors

Abstract

The positron distribution of charge along the (1 11) direction is calculated for elemental and compound semiconductors. The results show that the positron has a strong affinity for one sort of atom in binary semiconductors. This relative positron affinity may lead to the positron preferentially annihilating with the electrons of that sort of atom in compound semiconductors. The trends in going from Ge to CdTe through GaAs show an increase in positron affinity for the anion over the cation.La densite de charge des positrons a Btk calculee suivant la direction (1 11) pour des semiconducteurs simples et composes. Les resultats montrent que le positron a une grande affinite pour un type d'atome dans les semiconducteurs binaires. Cette affinite relative peut amener le positron a s'annihiler de preference avec les electrons de ce type d'atome du compose. La densitt de charge calculee pour plusieurs semicondbcteurs, de Ge a CdTe en passant par GaAs, montre une affinite du positron croissante pour l'anion plutBt que pour le cation.

Theoretical Calculation of Positron Annihilation Angular Correlation Anisotropy in GaP

“…The coefficients Cnk(C) are obtained by solving the Schrodinger equation. Similarly the positron wave function, is obtained in the same way as given by Aourag et al [7]. In terms of the electron and positron wave functions one can write e2'(p) as where…”

“…The positron-electron correlation potential was not taken in our calculation of the positron wave function. In the recent calculation of positron densities in compound semiconductors [7] it was found that the positron density is nearer to the anion site. In the case of ionic solids it was also found [8] that the positrons annihilate mostly near the anion.…”

Theoretical Studies of Positron Annihilation in GaP1?xNx

“…The positron wave function was determined through the ionic potential using the point-core approximation [40,52]. With the potential diverging at the ion core region the wave function is expected to converge with a high number of plane waves.…”

“…Si and Ge by different groups [33 to 39]. Since compound semiconductors are covalent materials with a degree of ionicity, they are expected to show different behavior compared to group-IV semiconductors, since the probability of the positron annihilating with the negative ion is greater than that with the positive ion [40]. In the case of ionic solids it was also found [41] that the positrons annihilate mostly near the anion.…”

Electronic and Positronic Distribution in the Ternary Alloy Hg1-xCdxTe

“…The nuclear charge can be expressed as a d-function at the origin of each cell. We shall adopt the point core approximation [11].…”