POTENTIAL FLUCTUATIONS DUE TO INHOMOGENEITY IN HYDROGENATED AMORPHOUS-SILICON AND THE RESULTING CHARGED DANGLING-BOND DEFECTS

We consider the thermodynamic equilibrium statistics of the dangling-bond undercoordination defect in undoped hydrogenated amorphous silicon (a-Si:H), assuming that material inhomogeneity causes electrostatic potential fluctuations whose peak-to-peak magnitude is greater than the (positive) effective correlation energy. We show that the fluctuations cause the formation of significant concentrations of charged dangling-bond defects. The negative defects form in regions of high potential and have transition energies below the Fermi energy (EF). The positive defects form in regions of low potential and have transitions above EF. We discuss evidence for the model and consequences of the charged dangling-bond defects for electron-spin resonance, transport, and photostability in a-Si:H. © 1990 The American Physical Society.