Band structures of II-VI semiconductors using Gaussian basis functions with separableab initiopseudopotentials: Application to prediction of band offsets

Abstract

We describe the implementation of a separable pseudopotential into the dual space approach for ab initio density-functional calculations using Gaussian basis functions. We apply this Gaussian dual space method ͑GDS/DFT͒ to the study of II-VI semiconductors ͑IIϭZn, Cd, Hg; VIϭS, Se, Te, Po͒. The results compare well with experimental data and demonstrate the general transferability of the separable pseudopotential. We also introduce a band-consistent tight-binding ͑BC-TB͒ model for calculating the bulk contributions to the valenceband offsets ͑VBO's͒. This BC-TB approach yields good agreement with all-electron ab initio GDS/DFT results. Comparisons between BC-TB results of VBO obtained with and without p-d coupling demonstrate quantitatively the importance of d electrons and cation-d -anion-p coupling in II-VI systems. Agreement between ab initio results and experimental results is excellent.

Epitaxial growth of colloidal hydrophilic lattice matched HgTe/CdTe core/shell nanocrystals for UV luminescence

“…The effect of LEEH concentration vis-à-vis the size and size distribution are also reflected in their optical properties which we discuss in a later section. According to Chen et al [21] and Adachi [22], the bulk lattice compressibility of bulk HgTe and CdTe are respectively 47.6 GPa and 44.5 GPa and CdTe is most compressible. This implies that CdTe is softer whereas HgTe is the hardest in the IIeVI group of semiconductors [21,22].…”

“…According to Chen et al [21] and Adachi [22], the bulk lattice compressibility of bulk HgTe and CdTe are respectively 47.6 GPa and 44.5 GPa and CdTe is most compressible. This implies that CdTe is softer whereas HgTe is the hardest in the IIeVI group of semiconductors [21,22]. This further suggests that the strain will not affect the core but will affect the shell.…”

Extending the spectral range of CdSe/ZnSe quantum wells by strain engineering

“…For the CdSe QWs we assumed cubic crystal structure and the main material parameters as summarized in Table II together with a valence band offset of 20% to ZnSe [44]. We assumed excitonic transitions in the CdSe QWs, considered the exciton binding energy and calculated the average strain energy density across the ZnSe/CdSe/ZnSe layer system with the nextnano 3 software.…”

Microscopic Origin of Electrical Compensation in Arsenic-Doped HgCdTe by Molecular Beam Epitaxy: Density Functional Study

“…The calculated ground lattice constant for bulk HgTe was 6.66 Å , in agreement with the experimental value 6.46 Å . 15 We used a 64-atom supercell and a 9 · 9 · 9 k-points Monkhorst-pack mesh. All internal structural parameters were fully relaxed until the Hellmann-Feynman (HF) forces were below 0.01 eV/ Å .…”