Characterization of (As.Te)1-xSex thin films

1-x Se_x thin films (where x=0.20, 0.23, 0.27, 0.32 and 0.44) have been studied. Increasing the Se content was found to increase the optical energy gap and the activation energy for conduction of the investigated films. The optical energy gap of the As_0.40Te_0.40Se_0.20 films was increased up to 1.21 eV by increasing the film thickness to ∼120 nm, while thermal annealing at 480 K reduced it down to 0.83 eV. The decrease of the optical gap is discussed on the basis of amorphous–crystalline transformations. Received: 07 July 1997/Accepted: 30 July 1997