Hydrogen kinetics in a-Si:H and a-SiC:H thin films investigated by real-time ERD

Abstract

Hydrogen effusion from hydrogenated amorphous silicon (a-Si:H) and amorphous silicon carbide (a-Si1 xCx:H) thin films during a temperature ramp between RT and 600 C was studied by in situ realtime 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 cm2/s were obtained. Applied to an non-stoichiometric a-Si1 xCx: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 cm2/s, respectively.