RELATED STRUCTURAL, ELECTRICAL AND PHOTO-ELECTRICAL PROPERTIES OF VACUUM-DEPOSITED GAP THIN-FILMS

GaP thin films with thicknesses from 0.1 to 0.6 μm were prepared by the thermal evaporation of the compound GaP onto quartz substrates at temperatures from ambient temperature to 740 °C. The properties of the films depended strongly on substrate temperature and deposition rate. With increasing substrate temperature the film structure changed from amorphous to textured polycrystalline with a strong [100] texture. The temperature of the amorphous-to-crystalline transition depended on deposition rate and was found to be 360 and 400 °C for deposition rates of 2 and 10 Å s-1 respectively. At these temperatures the electrical resistivity of the films fell sharply from 108 Ω cm to a minimum value of 5 × 104 Ω cm, after which it increased again with increasing temperature. The amorphous films exhibited a moderate photosensitivity with a maximum value near the temperature of the structural transition; above this temperature the films lost their photosensitivity completely. The spectral dependence of the photoconductivity was measured and an attempt was made to interpret the observed spectra. © 1979.