Photocapacitance relaxation and rigidity transition in GexAsxSe1−2x amorphous films

The photocapacitance relaxation of Ge
_x
As
_x
Se
_1-2x
thin films is investigated for x=0.05, 0.07, 0.09, 0.14, 0.16, 0.18, 0.20 0.25 and 0.30. Compositional dependencies of the low-frequency dielectric permeability, decay time constant and the Kohlrausch parameter of nonexponentiality are deduced from these data. All parameters show two compositional thresholds, one situated near the x
_c
(1)=0.09, and another - near the x
_c
(2)=0.16-0.18. These phase transitions have been identified in the bulk samples by means of a differential-scanning calorimetric method (P. Boolchand et al., Europhys. Lett., 52, p. 633, 2000).