Correlation between the results of charge deep-level transient spectroscopy and ESR techniques for undoped hydrogenated amorphous silicon

Abstract

Results of charge deep-level transient spectroscopy (DLTS) and electron spin resonance (ESR) measurements on undoped hydrogenated amorphous silicon $(a$-Si:H) clearly demonstrate that a group of gap states with a mean energy of 0.82 eV as observed in charge DLTS experiments for a-Si:H based metal/oxide/semiconductor structure is the same as the $g=2.0055$ ESR defect (the ${D}_{z}$ component). This correlation provides a distinct marker for charge DLTS technique. We obtained a very good fit to spectra obtained on undoped a-Si:H in the annealed state whilst there is some discrepancy between the experimental and simulated spectra for the light-soaked state. The first quantitative comparison of defect pool model with gap states directly observed by charge DLTS offers not only additional data for more accurate identification of all the intrinsic and light-induced defects. This also renders distinct counter-evidence to recently published conjectures about the creation of another charged defect during early stage of Staebler-Wronski effect. By contrast, our presented results clearly argue for opposite process, i.e., decay of positively charged defect states ${D}_{h}.$