Effects of UV light on the deposition kinetics and optoelectronic properties of a-Si:H films deposited by RF glow discharge

We here present the results of a study of the growth kinetics and optoelectronic properties of a-Si:H films deposited on glass substrates by RF glow discharge and submitted to the UV light emitted by an XeCl excimer laser during their growth. The comparison to reference samples deposited under the same plasma conditions but without the UV irradiation shows that the UV light produces an acceleration of the initial stage of the deposition and a small increase of the average deposition rate. The UV light induces an increase of the film porosity and small changes on the optical properties and hydrogen content of the films. The activation of the initial stage of deposition and the increase of the film porosity were not observed either on crystalline silicon or on a-Si:H substrates. Whereas the defect density and the Urbach energy of the films are slightly reduced by the exposure to the UV light, the dark conductivity is strongly increased for the films deposited at low substrate temperature (50°C).