Empirical pseudopotential calculations of Cd1−xMnxTe

Abstract

Empirical pseudopotential calculations for the entire range of alloy concentrations of cubic Cd 1Ϫx Mn x Te are presented. The atomic form factors have been deduced empirically by fitting the band structure to spectroscopic data available from the literature. The pseudopotential band structures indicate optical bowing may occur in the alloy Cd 1Ϫx Mn x Te and have been used to determine the effective masses of the electron and light, and heavy holes, which for CdTe are in agreement with accepted values. The effective masses for Cd 1Ϫx Mn x Te are given for the first time, and are expressed as first-and second-order polynomials in x. The implications of these results for spectroscopic experiments are discussed.

The structural dependence of the effective mass and Luttinger parameters in semiconductor quantum wells

“…The entity N is the number of lattice constants in a superlattice unit cell and the m are the integers satisfying mрN. ⌽ n,k,s is generated by the standard local pseudopotential calculation including spin-orbit coupling, 11,25,33 i.e., by directly diagonalizing the matrix equation…”

“…In comparison with this, the solid lines are the results of implementing the approach of Ekenberg. 43 Basically this involves deducing the effective mass from the bulk ͓100͔ bandstructure 25 at the band energies corresponding to the quantum well confinement energies. It is apparent that while the nonparabolicity of the bulk band structure is contributing to the variation in the effective mass, it is not sufficient to explain the dependency.…”

“…Curve ͑iii͒ is from the k•p model 2, which uses constant Luttinger parameters appropriate to bulk effective masses deduced from the bulk pseudopotential calculations shown in Table I. 25 Curve ͑iv͒ is from the k•p model 1, which uses constant Luttinger parameters derived from the experimental observations of bulk materials. 44 Figure 8 displays the equivalent data of Fig.…”

“…In the present article, which is an extension of our recent work on the band structure and effective masses of the bulk Cd 1Ϫx Mn x Te alloy, 25 we perform the first empirical pseudoa͒ Electronic mail: f.long@apphys.hull.ac.uk potential calculations of ͑001͒CdTe/Cd 1Ϫx Mn x Te superlattices and quantum wells. These results are then compared with those from a simple single band model and with a multiband k•p model, both of which encompass the envelope function and effective mass approximations.…”

Electronic properties and charge density of Be x Zn1 − x Te alloys

“…To compute band structure and charge density for the alloys, virtual crystal approximation (VCA) may be applied. Unlike metallic alloys the approximation has worked reasonably well to examine bandgaps, effective masses and bowing in other III-V and II-VI ternary and multi-component semiconductor alloys (Long et al 1996;Bechiri et al 2002;Bouarissa 2003;Ben Fredj et al 2007;Patel and Joshi 2007). However, for better description, effect of disorder needs to be considered.…”