Specific Features of Content Dependences for Energy Gap in InxTl1-xI Solid State Crystalline Alloys

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.