Meyer-Neldel rule in charge-trapping metastability inp-type hydrogenated amorphous silicon

Measurements of capacitance transients due to charge-carrier emission from metastable defects in p-type hydrogenated amorphous silicon (a-Si:H) $p/n$ junction structures show that both holes and electrons can be metastably trapped in the p layer. At 350 K electrons and holes are emitted at the same rate, thereby defining the isokinetic temperature (Tᵢₛₒ) for the Meyer-Neldel rule. The enthalpy changes for hole and electron emission are 0.94 and 0.51 eV, respectively. Charge emission rates are measured above and below Tᵢₛₒ. The entropy changes for hole and electron emission are 31 and 17 Boltzmann constants, respectively. Below Tᵢₛₒ electrons are emitted faster than holes, and above Tᵢₛₒ the reverse is true. These relative changes in emission rates are a direct consequence of the large entropy changes in the defect reactions. Tᵢₛₒ within experimental error, is the same as the H glass equilibration temperature (360 K) measured by others in p-type a-Si:H. Arguments are presented suggesting that the defect reactions measured here are involved in H glass equilibration.