OBSERVATION OF CONFIGURATION SWITCHING OF THE D-CENTER IN A-SI-H

We report evidence for two configurations of the D- center in the same a-Si:H sample: one possessing the usual electron thermal emission energy of roughly 0.9 eV (D-) and the other possessing a thermal emission energy between 0.6 to 0.7 eV (D-)*. The (D-)* state is observed soon after the capture of electrons into D(o) states within the deep depletion region of a Schottky barrier diode. As the time of occupation of the defect increases we observe that the emission rate decreases dramatically, implying a significant increase in its thermal emission energy. We have also found that this state exhibits an usually large optical energy threshold, near 1.3 eV. This implies a large degree of lattice relaxation between the (D-)* state and the conduction band.