Assessment of lattice relaxation effects in transitions from mobility gap states in hydrogenated amorphous silicon using transient photocapacitance techniques

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Abstract
We have employed junction photocapacitance and thermal transient capacitance measurements in n-type doped hydrogenated amorphous silicon and have identified, within each of a series of samples, the optical transitions: D−→D0+e and D0→D++e, and the thermal transitions: D−→D0+e and D+→D0+h, where D−, D0, and D+ denote the three charge states of Si dangling bond defect. We have also correlated the optical and thermal transitions associated with the valence bandtail states. Lattice relaxation energies are found to be less than 0.1 eV for the dangling bond transitions, but as large as 0.5–0.6 eV for the valence bandtail states. We also determined a value of Ueff for the D−/D0 splitting of 0.24±0.07 eV.