Optical constants and associated functions of CdGa₂Se₄ thin films

Abstract

A polycrystalline stoichiometric sample of the ternary compound CdGa2Se4 was prepared and characterized by x-ray diffraction analysis. Lattice parameters were determined and compared with data in the literature. CdGa2Se4 thin films were prepared by thermal evaporation under vacuum (10−3 Pa). X-ray diffraction analysis of the deposited films revealed that, the as-deposited films were amorphous in nature and an amorphous-to-crystalline phase transition with a preferred orientation along (112) could be obtained by thermal annealing of the as-deposited films at 425 K for 0.5 h.The optical constants of the deposited films were determined in the spectral range 450–2500 nm. A graphical representation of log(α) versus log(1/λ) shows two distinct, linear parts confirming the existence of both direct and indirect optical transitions. The corresponding band gap values were determined. The refractive index dispersion in the transmission and low absorption region is adequately described by the single oscillator model, whereby the values of the oscillator strength, So, oscillator position, λo, dispersion parameter Eo/So and the high-frequency dielectric constant, ε∞ were calculated. The effective number of valence electrons per atom, n0,eff and the static dielectric constant, ε0,eff are deduced via the use of sum rules and are used to interpret the obtained optical data.

Transparent CdO/n-GaN(0001) heterojunction for optoelectronic applications

“…High-mobility electrons moving on the surface and in the bulk are exposed to energy loss. The surface energy loss function and volume energy loss function of the optical materials are due to the real and imaginary parts of the complex dielectric constant [47,48], The plots of the volume and surface energy loss vs. hν in the main absorption range for CdO films are shown in Fig. 9a and b.…”

Phase diagram of the CdGa2Se4–Sb2Se3 system and single crystal growth of CdGa2Se4

“…The optical band gap at 298 K, directly measured from the absorption spectra, is 1.95±0.05 eV. This value is significantly different from the energy gap of undoped CdGa 2 Se 4 [3][4][5], which also indicates a certain solid solution range of the ternary compound.…”

“…The CdGa 2 Se 4 compound belongs to the wide-gap semiconductors, and is known as a luminescent and photosensitive material [1,2]. Its optical properties were studied in [1,[3][4][5][6][7][8], both on thin films and bulk crystals. The energy gap was reported to be 2.41 eV [3], 2.51 eV [4], or 2.33 eV [5].…”

“…Its optical properties were studied in [1,[3][4][5][6][7][8], both on thin films and bulk crystals. The energy gap was reported to be 2.41 eV [3], 2.51 eV [4], or 2.33 eV [5]. The low-temperature (LT) modification of CdGa 2 Se 4 crystallizes in the tetragonal structure of cadmium thiogallate or defect chalcopyrite (space group І, а = 0.5743, с = 1.0756 nm [9]).…”

Role of the Crystal Lattice Constants and Band Structures in the Optoelectronic Spectra of CdGa2S4 by DFT Approaches

“…The electrophotographic layers of these semiconductors illustrate a photographic distinction with high quality and great resolution . CdGa 2 Se 4 can be exploited in a variety of nonlinear optical mediums such as gyrotropic media, solar units, detectors, and temperature sensors . AgGaS 2 , CdGa 2 S 4 , and CdGa 2 Se 4 crystals are widely used in various light deflectors .…”