Hydrogenated amorphous silicon deposited by DC magnetron sputtering at high temperature

In this work we report some results obtained on hydrogenated amorphous silicon (a-Si:H) deposited by DC magnetron sputtering at high rate between 15 and 20 Å/s and at high temperature between 773 and 873 K. The activation energy of the conductivity decreases from 0.9 to 0.55 eV for the films deposited at 773 and 873 K, respectively. An increase of the deposition temperature, up to 873 K, leads to a higher photoconductivity at room temperature. The maximum value obtained for the deposited film at 873 K is approximately 5×10−5 (Ω cm)−1 under 100 mW white light. The defect density (Nd) and the Urbach tail (E0), extracted from PDS spectrum, increase when the deposition temperature increases to 873 K. These structural characteristics cross through a minimum value of Nd=1017 cm−3 and E0=70 meV for films deposited at 823 K. These values reach 6–9×1017 cm−3 and 0.11–0.13 eV for films deposited at 873 K. In spite of these characterization results, the best film sensitivity to the white light is obtained for the films deposited at 873 K.