Observation of Configurational Switching of Deep Defects in a-Si:H Using Thermal Step Insertion During Capacitance Transient Measurements

Abstract

AbstractIn standard, isothermal capacitance transient measurements, configurational changes in defect states are normally very difficult to identify because, depending on the relative rates of thermal emission to the configurational relaxation, charge will be emitted predominantly from only one configuration. We have found, however, that employing a thermal step during the emission phase of the transient enhances the effect of defect relaxation; one can then observe the resultant switch between distinct configurations. We have applied this method quite successfully to lightly doped n-type a-Si:H samples by varying the overall temperature (between 270K and 350K) and the magnitude of the temperature switch (from 20K to 35K). For the smallest temperature steps, the resultant transients suggest two distinct configurations that, we believe, reflect only a fraction of the many latent configurations that account for the full range of relaxation possible.