Search

The presented main studies of point defects in CdGa2Se4 chalcopyrite are considered to quantify the formation energies of three possible models of Cd, Ga and Se vacancy defects using various local density approximation (LDA) and general gradient approximation (GGA) approximations. Using supercells with 56 atoms, interatomic distances were calculated both for an ideal cell and a supercell containing vacancies. It was found that interatomic distance does not change only in a supercell containing Ga vacancy. Investigation shows that the Ga vacancy has a high defect formation energy (DFE) among other intrinsic vacancies and is therefore unstable. We found that for all vacancies, − 2 charge states are favorable. [ABSTRACT FROM AUTHOR]

The presented main studies of point defects in CdGa2Se4 chalcopyrite are considered to quantify the formation energies of three possible models of Cd, Ga and Se vacancy defects using various local density approximation (LDA) and general gradient approximation (GGA) approximations. Using supercells with 56 atoms, interatomic distances were calculated both for an ideal cell and a supercell containing vacancies. It was found that interatomic distance does not change only in a supercell containing Ga vacancy. Investigation shows that the Ga vacancy has a high defect formation energy (DFE) among other intrinsic vacancies and is therefore unstable. We found that for all vacancies, − 2 charge states are favorable. [ABSTRACT FROM AUTHOR]

InAs-CrAs systems are synthesized by the vertical Bridgman–Stockbarger method. XRD analysis and microstructural study of InAs-CrAs composites show that CrAs metallic inclusions are uniformly distributed in the InAs matrices. By investigating of microstructure of InAs-CrAs eutectic composite by electron microscope, it has been established that the interfacial zone between the semiconductor matrix and metallic inclusions is generated. In computations of effective electrical and thermal conductivity of the composite were taken into account the role of these interfacial zones. [ABSTRACT FROM AUTHOR]

Crystallization kinetics of 30-nm-thick amorphous TlIn1 – xSnxSe2 films produced by thermal evaporation under high vacuum in a dc electric field E = 3000 V/cm have been studied by kinematic electron diffraction. The results demonstrate that the formation of the crystal structure of the amorphous films during heat treatment follows Avrami–Kolmogorov relations. Kinetic curves of the phase transformation demonstrate the effect of an electric field on the temperature range of film crystallization and on the activation energies for nucleation and subsequent nucleus growth. The total activation energy for the crystallization process has been determined to be Etotal = 44.92 kcal/mol. The observed diffraction lines of the polycrystalline TlIn0.93Sn0.07Sе2 films in their kinematic electron diffraction patterns can be indexed in tetragonal symmetry (sp. gr. = I4/mcm [12]) with unit-cell parameters a = b = 0.8358 nm and c = 0.7086 nm. After storage of the films in vacuum at room temperature for more than two months, no changes were detected in their quality or diffraction pattern. [ABSTRACT FROM AUTHOR]

The theory of free-carrier absorption is given for quantum well wire for the case where the carriers are scattered by confined longitudinal-optical (LO) phonons and the radiation field is polarized along the length of the wire. Both the multisubband structure and confined phonon modes are considered together. The free carrier absorption coefficients are calculated taking into account all possible LO phonon modes as well as all possible electron intersubband transitions. The results show that the absorption coefficient decreases with increasing the photon frequency and decreases with temperature. It was found that in quantum wire the electron-optic phonon interaction give a greater contribution to the absorption than the electron-confined LO phonon interaction. The results are interpreted in terms of confined LO phonons-assisted transitions between size quantized subbands. [ABSTRACT FROM AUTHOR]

The intersubband optical absorption is investigated in parabolic quantum wires in the presence of a tilted magnetic fields. We show that for increasing magnetic field the intersubband absorption peak is shifted to higher energies and its amplitude is increased, too. In particular, it has been shown that the direction of the magnetic field plays a significant role in the intersubband optical absorption. [ABSTRACT FROM AUTHOR]