Influence de la température de substrat sur la croissance et les propriétés des films minces de silicium amorphe déposés par pulvérisation cathodique

Abstract

We deposit thin films of a-Si:H by RF diode spray on substrate with temperatures varying from 200 to 500 °C. Knowing that this deposition method is violent when compared with the plasma-assisted deposition method, we have used low RF power to limit the energy of the Ar ions bombarding the surface of the growing film. Characterization of the films by UV–visible absorption spectroscopy suggests that the influence of the substrate temperature can be classified into three different regimes: (i) low temperature, Ts < 300 °C: the films show a strong disorder, the hydrogen is bound only in the polyhydric configuration; (ii) intermediate temperature, 300 °C < Ts < 400 °C: film growth is rapid, the films present a lower defect density; this may be the best regime to make good quality a-Si:H films using the spraying method; (iii) high temperature, Ts > 400 °C: the films are more organized, but less hydrogenated. The substrate temperature influences the film properties by modifying the growing mechanism through a control of the reactions taking place at the plasma–substrate interface, where the hydrogen dynamics play a fundamental role.[Journal translation]