Low-Temperature Raman Scattering in TlGaxIn1−xS2 Layered Mixed Crystals: Compositional Dependence of the Mode Frequencies and Line Shapes

Layered semiconductors have become increasingly interesting due to their structural properties and potential applications in optoelectronics. Their quasi-two-dimensionality, optical and photoconductive properties, and other features attract investigators in an effort to acquire a better insight into the physics of these compounds. Layered ternary crystals TlInS2 and TlGaS2 are the anisotropic crystals whose properties have recently become the subject of extensive research [1–8]. A high photosensitivity in the visible range, high birefringence in conjunction with a wide transparency range of 0.5−14 μm make these wide band gap crystals useful for optoelectronic applications [9]. TlInS2 and TlGaS2 belong to the interesting group of layered ternary semiconductors with the chemical formula TlBX2, where B = In or Ga and X = S or Se. The lattice of TlInS2 and TlGaS2 consists of strictly periodic two-dimensional layers arranged parallel to the (001) plane. Each successive layer is rotated by right angle with respect to the previous one. Interlayer bonding is formed between ∗corresponding author; e-mail: [email protected], on leave from Physics Department, Baku State University, Baku, Azerbaijan