Structural Properties of GexSe1-x Thin Films Prepared by Semi-closed Space Technique

Bulk and thin film GexSe1-x alloys have been prepared with 0.1≤X≤0.5.
The bulk materials were obtained by quenching from the melt. They have been
used as source materials to produce thin film samples using the thermal
evaporation method (semi-closed space technique). The composition of the
obtained films was checked against the bulk ones by X-ray fluorescence (XRF)
technique. X-ray diffraction patterns of the obtained compositions revealed the
presence of some crystalline inclusions in the amorphous matrix for some
compositions. Glass transition temperature measurements showed a maximum
in the range X=0.25 to 0.32 where the glass forming ability is optimum.
Measurements of the temperature dependence of the steady state dark current
as a function of the Ge content has been recorded during heating and cooling
cycles. A compensation effect has been found and characterized with two
compensation temperatures, during the cooling cycle. Optical transmission,
(UV) and infrared (IR), measurements have been performed. Energy band gap,
width of the band tail and the refractive index have been calculated. Results
have been interpreted in terms of the structural behavior of the samples under
investigation in view of the models presented in literatures.