EFFECT OF ANNEALING ON THE OPTICAL-PROPERTIES OF IN2TE3 THIN-FILMS

Several In2Te3 thin films of different thickness were prepared in a va cuum of 10(-5) Torr onto glass and quartz substrates held at about 300 K during the deposition process. X-ray diffraction analysis showed th at the prepared samples in bulk or as-deposited thin-film forms were i n an amorphous state. On annealing at 573 K, films have a beta-phase p olycrystalline structure. Transmittance and reflectance measurements i n the spectral range of 400-2500 nm for films deposited onto quartz su bstrates were used to calculate the optical constants (the refractive index n, the absorption index k and the absorption coefficient alpha) for In2Te3 films, either as-deposited or annealed at different tempera tures. The refractive index has anomalous behavior in the region of th e fundamental absorption edge. The allowed optical transitions were fo und to be nondirect transitions, with an optical gap of 1.02 eV for th e samples under test. The effect of annealing on the optical gap is in terpreted in terms of the density of states proposed by Mott and Davis .