Ab-initio local density approximation description of the electronic properties of zinc blende cadmium sulfide (zb-CdS)

Abstract

Self-consistent ab-initio electronic energy band structure of zinc blende CdS are reported within the local density functional (LDF) formalism. Our first principle, non-relativistic and ground state calculations employed a local density functional approximation (LDFA) potential and the linear combination of atomic orbitals (LCAO). Within the framework of the Bagayoko, Zhao, and Williams (BZW) method, we solved self-consistently both the Kohn-Sham equation and the equation giving the ground state density in terms of the wave functions of the occupied states. Our calculated, direct band gap of 2.39 eV, at the Γ point, is in accord with experiment. Our calculation reproduced the peaks in the conduction and valence bands density of states, within experimental uncertainties. So are the electron effective mass.

First principle electronic, structural, elastic, and optical properties of strontium titanate

“…[51][52][53][54][58][59][60] This method has been shown to lead to accurate ground state properties of many semiconductors: c-InN, 60 w-InN, 54 w-CdS, 53 c-CdS, 61 rutile-TiO 2 , 59 AlAs, 62 GaN, Si, C, RuO 2 , 51 and carbon nanotubes. 63 Instead of assuming that a single trial basis set will yield the correct ground state charge density of the solid, the BZW method entails a minimum of three self-consistent calculations with basis sets of different sizes and generally with different polarization functions, i.e., p, d, and f functions.…”

“…Such a basis set is verifiably converged for the description of occupied states. 53,60,61 We recall that Kohn and Sham, 104 in their original paper, explicitly stated the need to solve self consistently the pertinent system of equations defining LDA. The BZW method, as explained above, rigorously solves the system of equations in the sense explained above.…”

Improved performance of CdTe solar cells with CdS treatment

“…CdS has a direct band gap (E g ) of 2.42 eV at room temperature and a high optical absorption coefficient on the order of 4 Â 10 4 cm À1 at energies above the E g (Ekuma et al, 2011;Zarebska and Skompska, 2011), resulting in wide application of CdS in modern photoelectronic devices such as solar cells, optical detectors, piezoelectric transducers, light emitting diodes, and transparent UV protection devices. For example, CdS thin films are highly favorable in heterojunction thin-film solar cell applications because of their excellent optical E g , photoconductivity, and high electron affinity (Ferekides and Britt, 1994).…”

Photovoltaic Studies of Cd1-xCoxS Based Electrochemical Cells

“…Deposition using chemical bath is reported to be more advantageous than others 12,16,17,19,[23][24][25][26] ; because it is the conventional method with the advantages of economy, convenience, ease of scaling up to large area deposition and high degree of composition control 12,17,19,[23][24][25][26][27][28][29] . Cadmium sulfide and cobalt sulfide seems to be very promising among the chalcogenides because they have the direct band gaps of 2.42 eV and 1.10 eV respectively, high photosensitivity in the visible region of the spectrum, high coefficients of optical absorption and excellent stability with its n-type semiconductor characteristics 9,12,17,21,24,[30][31][32][33][34][35] . Further, both the end materials out of the series can be synthesized under the same conditions of preparation procedure and a variety of alloyed/mixed materials of the Cd 1-x Co x S kind with tailor made properties can be generated with ease and without the use of sophisticated instrumentation [16][17][18]21,22,35 .…”

“…Further, both the end materials out of the series can be synthesized under the same conditions of preparation procedure and a variety of alloyed/mixed materials of the Cd 1-x Co x S kind with tailor made properties can be generated with ease and without the use of sophisticated instrumentation [16][17][18]21,22,35 . These materials are therefore, of extremely importance for efficient use in optronic devices, especially in solar cell applications 12,[16][17][18]22,29,30,35 . It was therefore proposed to synthesize CdS, CoS and Cd 1-x Co x S (0 ≤ x ≤ 0.5) thin films under the same conditions of preparation using a liquid phase chemical bath deposition (LPCBD) method and to apply them for photovoltaic conversion through electrochemical photovoltaic cells.…”