Wide band gap tunability of bulk Cd1−xCaxO

Abstract

We report the lattice parameter variation and the band gap tuning of CdO with Ca by preparing thermodynamically stable Cd1−xCaxO solid solution in the entire composition range 0≤x≤1. The functional dependence of the lattice parameter on Ca concentration is found to deviate from Vegard’s law. The principal band gap is found to vary nonmonotonically over a wide range, from 1.4 to 3.9 eV for 0≤x≤0.8. First principles density functional theory calculations, using full potential linearized augmented plane wave methods also predict a nonlinear variation for the lattice parameter and the optical band gap with Ca concentration. From these calculations, contributions from volume deformation, electron transfer, and structural relaxation are estimated and the results are compared with experiments.

X-ray diffraction and extended X-ray absorption fine structure study of epitaxial mixed ternary bixbyite PrxY2−xO3 (x = 0–2) films on Si (111)

“…In the present case, the bond lengths exhibit a composition dependence which is in between the two limits. This behavior is similar to what has been found in III-V semiconductor alloys [42][43][44][45] 46 . This behavior has been understood as due to the fact that a bond angle distortion is energetically less costly than a bond length variation; the linear variation of the lattice parameter (Vegard's law) is thus accommodated locally by angular distortions and the bond lengths tend to remain relatively close to the sum of the ionic radii exhibiting a bimodal distribution.…”

First‐Principles Insight into the Composition‐Dependent Structure and Properties of γ‐Alon

“…From fitting, the b a was estimated to be 0.029 Å. The interesting analogous deviation has been noticed in many solid solution systems, such as Cd 1− x Ca x O and Mg 1− x Ni x O . In γ‐alon, the larger lattice bowing parameter is mainly derived from the distinct difference of ionic radius (0.08 Å) between N and O with tetrahedral coordination.…”

“…First‐principles calculation based on the density functional theory (DFT) have been widely used for studying the structure and properties of materials. In some solid solutions system, such as Al 4+2 x Si 2−2 x O 10− x , Zn 1− x Cd x O, Cd 1− x Ca x O, and Ca 1− x Sr x TiO 3 , the first‐principles calculation has been successfully performed to study on the effects of varying composition on structure and intrinsic properties . In γ‐alon, Batyrev and his coauthors have performed evolutionary algorithm calculations for several nitrogen concentrations to find out the lowest energy configurations of γ‐alon .…”

Orbital hybridization-induced band offset phenomena in NixCd1−xO thin films

“…Bernard and Zunger [57,58] have mentioned that consists of three major contribution. Firstly, the volume deformation (VD) due to change in the lattice dimension (XDR pattern gives us the signature of lattice deformation), secondly charge exchange (CE) in the alloy relative due to difference in the electronegativity of Cd and Ni atom and thirdly structural contribution (S) caused by cation-anion bond length relaxation in the alloy [59]. Therefore,…”