Optical energy gap and thermal diffusivity of Ge-Se semiconducting glasses

The photoacoustic (PA) technique was used to study the variation of the optical energy gap and to measure the thermal diffusivity of GexSe100-x (10 &le x &le 38) glasses. The optical energy gaps of samples with different values of x determined from the PA spectrum which also gives features of the optical absorption in the subband gap region. The variation of the thermal diffusivity with composition was also investigated. The observed behaviour is explained on the basis of chemical bonding between the constituents and the chemical threshold and mechanical percolation threshold behaviour of the network.