Optical spectra and band structure of Ag(x)Ga(x)Ge(1-x)Se2 (x = 0.333, 0.250, 0.200, 0.167) single crystals: experiment and theory

• Published in: The journal of physical chemistry. B Vol. 117; no. 48; pp. 15220 - 15231
• Main Authors: Reshak, A H, Parasyuk, O V, Fedorchuk, A O, Kamarudin, H, Auluck, S, Chyský, J
• Format: Journal Article
• Language: English
• Published: United States 05.12.2013
• Subjects: Crystallography, X-Ray; Gallium - chemistry; Germanium - chemistry; Models, Molecular; Molecular Structure; Quantum Theory; Selenium - chemistry; Silver - chemistry; Spectrophotometry, Ultraviolet
• ISSN: 1520-5207
• DOI: 10.1021/jp410786w

Theoretical and experimental studies of the Ag(x)Ga(x)Ge(1-x)Se2 (x = 0.333, 0.250, 0.200, 0.167) single crystals are performed. These crystals possess a lot of intrinsic defects which are responsible for their optoelectronic features. The theoretical investigations were performed by means of DFT calculations using different exchange-correlation potentials. The experimental studies were carried out using the modulated VUV ellipsometry for dielectric constants and birefringence studies. The comparison of the structure obtained from X-ray with the theoretically optimized structure is presented. The crucial role of the intrinsic defect states is manifested in the choice of the exchange correlation potential used. The data may be applicable for a large number of the ternary chalcogenides which are sensitive to the presence of the local disordered states near the band edges.