Specific Features of Content Dependences for Energy Gap in In_xTl_1-xI Solid State Crystalline Alloys

Abstract

A series of InxTl1−xI (x = 0.4−0.9) single crystalline solid state alloys were successfully synthesized by the vertical Bridgman method. For the first time the density functional theory based band structure calculations are performed and features of the band energy dispersion are discussed. Comparison with the experimental energy gap Eg obtained from the optical photoconductivity is discussed. An essential role of the localized defects and excitons in formation of the edge photoconductivity is analyzed. Relation between the crystal structure and photoconductivity of the materials studied is discussed. Also the origin of the principal valence and conduction bands is explored. Experimental measurements of the band gap Eg by the optical and photoconductivity methods have given opposite dependences with respect to the indium content x. Features of the photoconductivity spectra for different crystallographic directions have been discussed with taking into account the chemical bonds anisotropy.

Electronic Bands and Dielectric Functions of In0.5Tl0.5I Solid State Solution with Structural Defects

“…24 a possibility of forming the InI structure as a matrix for the TlI quantum dots inclusion is discussed. The reduction of the crystal unit cell dimensions b and c, and the unit cell volume V and the increase of dimension a together with the increase of content index x are the main features indicating the continuous structure changes of In x Tl 1Àx I 16 (in the previous Refs. [13][14][15][16][17][18] and [22][23][24][25][26][27] the convention a % c < b for the unit cell dimension was adopted).…”

“…[13][14][15] Their band gap E g varies within the 2.01-2.84 eV range. [13][14][15][16] The crystals possess a layered structure. However, in contrast to typical layered crystals of the A II B VII and A III B VI (CdI 2 , HgI 2 , GaSe, InSe) groups, 17,18 in which the van der Waals interlayer gaps are formed mainly by the corresponding anions, in In x Tl 1Àx I SSS, this weakest chemical bonding is probably created by indium and thallium cations and iodine anions.…”

“…The crystals InI and TlI cleave perpendicularly to the crystallographic b-axis. [13][14][15][16][17][18] Smooth controlled changes of the energy band gap E g , mechanical and photovoltaic characteristics and spectral range of the recombination radiation may be realized in them. Results of investigation of the band structure and photoconductivity with change of the indium versus thallium content of the crystals In x Tl 1Àx I are presented in the recent study.…”

“…Results of investigation of the band structure and photoconductivity with change of the indium versus thallium content of the crystals In x Tl 1Àx I are presented in the recent study. 16 So far, studies of the phonon spectra, mechanical and optical characteristics are known for In x Tl 1Àx I SSS. [24][25][26][27] In Ref.…”

Оптико-энергетические свойства тонких пленок CdS, полученных методом высокочастотного магнетронного распыления

“…Интегрирование по зоне Бриллюэна выполнялось по сетке 2 × 2 × 2 k-точек с помощью схемы Монхорста-Пака [15]. Спиновые степени свободы электронов в этом расчете не учтены [16].…”