Thermal-equilibrium defects in undoped hydrogenated amorphous silicon, silicon-carbon, and silicon-nitrogen

Temperature dependence of the thermal-equilibrium defect density in undoped a-Si:H, a-${\mathrm{Si}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{C}}_{\mathit{x}}$:H, and a-${\mathrm{Si}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{N}}_{\mathit{x}}$:H is obtained both by in situ electron-spin-resonance (ESR) measurements at elevated temperatures and by ESR measurements of frozen-in defects at room temperature. The experimental results confirm that the defects in these alloy films, even for films with the defect density as high as ${10}^{17}$ ${\mathrm{cm}}^{\mathrm{-}3}$, can reach thermal equilibrium above a certain temperature (200–350 °C). Thickness dependence of the defect density after various thermal treatments shows that only the bulk defect density increases with temperature, with the exception that thin a-Si:H films (