Optical properties of TlGa_xIn_1-xSe₂-layered mixed crystals (0.5 ≤ x ≤ 1) by spectroscopic ellipsometry, transmission, and reflection measurements

Band gap and refractive index tunability in thallium based layered mixed crystals

“…Recently, the room temperature spectroscopic ellipsometry measurements have been carried out on the layer-plane (001) surfaces of TlGa 1Àx In x Se 2 , TlGa(S 1Àx Se x ) 2 , TlGa 1Àx In x S 2 , and TlIn(Se 1Àx S x ) 2 mixed crystals. [20][21][22][23] The critical point energies in the above band gap region as a function of the composition in the studied mixed crystals were found from the analysis of the secondenergy derivative spectra of the complex dielectric function.…”

Spectroscopic Ellipsometry Studies and Temperature Behaviour of the Dielectric Function of TlInS2 Layered Crystal

“…A phenomenological approach applied for the description of the phase transitions in TlInS2 enabled qualitative agreement with the experimental dependence of thermodynamical functions on temperature to be obtained [3][4][5]. For these materials extensive temperature studies of acoustic [6], electrical [7][8][9][10][11][12], and optical [13][14][15][16] properties were carried out while ellipsometric studies of A III B III C VI (A  Tl, B  (In, Ga), C  (S, Se)) chalcogenides were subject of several publications [17][18][19][20][21][22][23][24][25][26].…”

“…In particular, an analysis of the second derivative spectra of the dielectric function for TlGaS2xSe2 (1-x) [17], TlGaxIn1-xS2 [18], and TlGaxIn1-xSe2 [19] solid solutions was performed. Note that for TlInS2xSe2(1-x) the analysis was carried out only for set of compositions (x  0.25, 0.5, and 0.75) at room temperature [20].…”

Composition dependence of lattice parameters and band gap energies of thallium based layered mixed crystals

“…Recently, the spectroscopic ellipsometry measurements have been carried out on TlIn 1-x Ga x Se 2 , TlGa(S 1-x Se x ) 2 , TlGa 1-x In x S 2 and TlIn(Se 1-x S x ) 2 mixed crystals in the spectral range of 1.2-6.2 eV [17][18][19][20]. The refractive indices, extinction coefficients, real and imaginary parts of dielectric function have been calculated from ellipsometric data.…”