Search

Hydrogen effusion from hydrogenated amorphous silicon (a-Si:H) and amorphous silicon carbide (a-Si 1− x C x :H) thin films during a temperature ramp between RT and 600 °C was studied by in situ real-time elastic recoil detection analysis. Point to point contour maps show the hydrogen depth profile and its evolution with the ramped temperature. This paper proposes a diffusion limited evolution model to study H kinetic properties from total retained H contents recorded in a single ramp. In a compact a-Si:H layer where H predominantly effuses at high temperatures between 500 and 600 °C, an activation energy value of ∼1.50 eV and a diffusion pre-factor of 0.41 × 10 −4 cm 2 /s were obtained. Applied to an non-stoichiometric a-Si 1− x C x :H film in the same range of temperature, the model led to reduced values of activation energy and diffusion prefactor of ∼0.33 eV and 0.59 × 10 −11 cm 2 /s, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Results of photoresponse, activation energy and light soaking measurements on selected hydrogenated nanocrystalline Si thin films are presented. The films were deposited by hot-wire chemical vapour deposition. Values of photoresponse better than 1×102 were obtained. They are lower for porous material as the crystalline volume fraction increases. Activation energy results are related to the intrinsic character and the microstructure of the films. Light soaking experiments show that the nanocrystalline films are very stable. Their amorphous counterparts attain a stable photoconductivity value after 300 h of illumination. [Copyright &y& Elsevier]