Thermally induced metastable defects in hydrogenated amorphous silicon and silicon-carbon alloy films

Thermally induced metastable defects in hydrogenated amorphous silicon (a-Si:H) and silicon-carbon alloy (a-${\mathrm{Si}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{C}}_{\mathrm{x}}$:H) films are studied by electron spin resonance (ESR) and conductivity measurements. We found that both undoped and P-doped a-${\mathrm{Si}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{C}}_{\mathrm{x}}$:H films exhibit thermal-equilibrium phenomena similar to those in a-Si:H although they have much higher defect densities. By heating the samples in situ during ESR measurements, we were able to directly observe the density of dangling bonds in both a-Si:H and a-${\mathrm{Si}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{C}}_{\mathrm{x}}$:H as the samples move from a frozen-in state into a temperature-dependent equilibrium. The influence of surface states and long-term drift of exposed surface on the thermal-equilibrium process has also been extensively investigated.