EPR INVESTIGATION OF A-SI-H AEROSOL-PARTICLES FORMED UNDER SILANE THERMAL-DECOMPOSITION

The dangling bond defects were investigated in a-Si:H particles formed under silane thermal decomposition in flow reactor. EPR together with hydrogen evolution method were used. The experimental results allowed us to conclude that there are two kinds of dangling bond defects in a -Si:H aerosol particles. The defects of the first kind are localized o n the surface of interconnected microvoids and microchannels (surface dangling bonds) and those of the second kind are embedded in amorphous silicon network (volume dangling bonds). The thermal equilibration of dangling bonds and temperature dependence of equilibrium dangling bon d concentration were investigated. It was found that at temperatures > 400 K the dangling bond concentration N-s reversibly depends on sample temperature. The Volume dangling bond concentration increases with te mperature increasing (the effective activation energy of dangling bond formation U> 0), and the surface dangling bond concentration decrease s with temperature increasing (U < 0). It has been found that EPR line is considerably asymmetric for samples with high hydrogen content and for low hydrogen content the EPR line is weakly asymmetric. A conclus ion was drawn that the asymmetry degree depends on amorphous silicon l attice distortions. This conclusion has been confirmed by EPR spectra simulations.