On the Band Structure of CdGa₂S₄

Abstract

BYThe band structure of CdG%S4 is calculated by the pseudopotential method in /1/ and by the method of localized orbitals in /2/. According to the data of /1/ the top of the valence band meets the r2v representation, whereas according to /2/ it complies with r3v+ r4v. The conduction band bottoms in /1/ and /2/ a r e conform to the TlC representation.ly obtained data on the nature of optical transitions and their values in the fundamental absorption edge region a r e conflicting. In /6/ the reflection spectra within the fundamental absorption region (up to 6 eV) a r e presented without any interpretation. In /3 t o 5/ we studied the double reflection spectra of CdG%S4 in the region of 3 to 6 eV at polarized radiation and their interpretation was given on the basis of a group-theoretical analysis and a correlation with the optical spectra of compounds having chalcopyrite structure.The optical spectra of CdG%S4 have been studied in /3 to 7/. The previous-All the earlier measurements were conducted by stationary methods which did not allow to detect a fine structure. Therefore in this study the L -modulated reflection spectra have been investigated with polarized radiation at 300 K i n order to provide a more accurate picture of the band spectrum of Cdc%S4.pendence of the absorption coefficient on the energy of incident photons at polarized radiation. The presence of an isotropic point at h v = 3.38 eV where K , , = = K, is typical of this spectrum. In /6/ the dependence of the absorption coefficient on the energy of incident photons at polarised radiation is also presented but no isotropic point has been detected. The authors of /6/ apparently used thick specimens. Owik to the unambiguous relationship between the absorption coefficient and the refraction index, one may suppose that the observed depend-the region of the fundamental absorption edge of CdG%S4 (in Experimental results and their discussion The inset in Fig. 1 gives the de-1 ) Narimanova 33, Baku 143, USSR.

Optical constants and associated functions of CdGa2Se4 thin films

“…For further analysis of the optical data a number of useful, associated relations can be derived that link the real and imaginary parts of the dielectric function and the optical constants, that is, the so-called dispersion relation and sum rules, which have been extremely valuable in analysing and testing optical constant data. The dispersion relation for CdGa 2 Se 4 films is described well by a single-term Sellmeier oscillator [25]: Assuming that the high frequency properties of CdGa 2 Se 4 could be treated as that for a single oscillator of an empty lattice at infinite wavelength, λ −1 → ∞, and applying the simple classical dispersion relation [24], the value of the highfrequency dielectric constant, ε ∞ estimated from figure 5 using this procedure was found to be 6.78, in good agreement with the value of ε ∞ = 6.7 for E⊥C determined from the reflection spectra of CdGa 2 Se 4 single crystals [26] and slightly less than 7.29, determined from the optical phonon spectra of CdGa 2 Se 4 [27].…”

“…Single crystals of CdGa 2 Se 4 were prepared using the chemical transport reaction technique, with iodine as a transport agent [10][11][12]. X-ray diffraction analysis showed that CdGa 2 Se 4 single crystals crystallized into tetragonal structures with the space group S 4 2 and the lattice parameters were a = 5.73 1 Å, b = 10.75 1 Å, [13].…”

Composition‐dependent behavior of Co(d7) optical transitions in Cd1–xCoxGa2S4 mixed crystals

“…Cd 1-x Co x Ga 2 S 4 is a new quaternary solid solution based on CdGa 2 S 4 and,CoGa 2 S 4 which are ternary compounds with the general formula AB 2 C 4 . The CdGa 2 S 4 is a wide-gap semiconductor (E g = 3.5 eV at 300 K) with high photoconductivity and strong luminescence in the visible region [1,2]. Also, CoGa 2 S 4 belongs to the class of materials referred to as semimagnetic semiconductors or diluted magnetic semiconductors [3].…”

Optical properties of Cd(Ga 1– x Tm x ) 2 S 4 ( x = 0.01) single crystals

“…1 Introduction CdGa 2 S 4 is a wide-gap semiconductor (Eg = 3.5 eV at 300 K) with high photoconductivity and strong luminescence in the visible region [1][2][3][4]. These desirable properties make this compound a promising optoelectronic material.…”