Effects influencing the structural integrity of semiconductors and their alloys

Abstract

The bond length and energy changes of the constituents of alloys relative to their pure crystal values are calculated from an extension of Harrison’s method. It is demonstrated that the already weak HgTe bonds are destabilized by adjacent CdTe, HgS, or HgSe, but are stabilized by ZnTe. It is also argued that dislocation energies and the hardness of semiconductors vary as a high inverse power of the bond length of the constituents. Hence, the shorter ZnTe bond as an additive should improve the structural properties of HgTe and CdTe. Experiments that support these predictions are noted. The electronic transport properties of 0.1 eV band gap HgZnTe are about the same as those of HgCdTe, and the structural properties of the Zn compound are superior; thus, we conclude that HgZnTe is likely to be the better material for IR devices.

Fracture and Hardness of Semiconductor Alloys.

“…We find that dEv/dx for Hg in HgCdTe is slightly positive, contrary to our earlier suggestion based only on bond energies. 9 However, dE,/dx for Hg in HgZnTe is even larger, a trend in agreement with our prior predictions. In this first approximation, Hg vacancy formation energies in HgZnTe are always larger than those in HgCdTe, for concentrations producing band gaps in the range 0.1 to 0.3 eV.…”

“…9 However, it is not sufficient to consider simply the bond energies when predicting vacancy formation energies. The creation of a vacancy involves not only the breaking of four bonds, but results in a back-bonding relaxation of the bonds about the vacancy site in the bulk, and this energy can be substantial.…”

History of HgTe-based photodetectors in Poland

“…The theoretical consideration that the weak HgTe bond is destabilised by alloying it with CdTe, but stabilised by ZnTe [64], has stimulated interest by many groups world− wide in the growth and properties of the HgZnTe alloy sys− tem as the material for photodetection application in the in− frared spectral region. The question of lattice stability in the case of HgMnTe compound is rather ambiguous [40].…”

Model of the two well potential for Hg-atoms in the Hg1 - xCdx Te alloy lattice

“…It means that substitution of the Hg-cation by a Cd-cation does not cause lattice deformations. On the other hand, the week Hg-Te bond (introducing of Cd-atoms to the lattice weaken this bond more in Hg 1− x Cd x Te [6]) causes such self-defects as Hg-vacancy to be thermodynamically stable in the Hg-sublattice [7]. The problem of Hg-vacancies in the lattice is also discussed in papers dedicated to phonon spectra of MCT [8][9][10][11][12].…”