CHARGE-DEFECT THERMODYNAMIC-EQUILIBRIUM AND METASTABLE DEFECTS IN AMORPHOUS-SILICON

A thermodynamic equilibrium description of the high-temperature (150-2 50-degrees-C) steady-state behavior of light-induced defects in amorph ous silicon is presented. The entropy and enthalpy of dangling-bond fo rmation are quantified. In contrast to the behavior of vacancies in si ngle-crystalline silicon the creation of the dangling-bond defect in a morphous silicon produces negative entropy and enthalpy changes indica ting that lattice relaxations contribute to the free-energy changes. O ver the temperature range examined, the creation of dangling bonds low ers the free energy due to the relatively large negative enthalpy chan ge. Practical issues such as the estimation of the saturated dangling- bond density resulting from given illumination level at temperatures t oo low to experimentally observe true saturation are also considered.