Signature of the weak bond-dangling bond conversion process in a-Si:H as seen by total photoelectron yield spectroscopy

Ristein J, Ley L (1993)

Publication Type: Conference contribution

Publication year: 1993

Journal

Materials Research Society Symposium - Proceedings Materials Research Society

Publisher: Materials Research Society

Edited Volumes: Materials Research Society Symposium Proceedings

Book Volume: 297

Pages Range: 207

Conference Proceedings Title: MRS Proceedings

Event location: Pitsburg

Abstract

Photoelectron Yield Spectroscopy is one of the most direct methods to study the density of gap states of amorphous semiconductors. We have made use of it to investigate the transient changes of the density of gap states of a-Si:H upon illumination with above-band-gap light. An excitation density of 50 mW/cm² of 532 nm light from a frequency doubled Nd-YAG laser was modulated with frequencies between 0.1 Hz and 10 KHz and the transient response of the photoelectron yield signal was monitored by gated electron counting or a lock-in amplifier. From this we deduce a reversible increase of the occupied density of defect states under illumination with a maximum Δg to approximately 10¹⁷ cm^-3 eV^-1 at about 0.3 eV below the Fermi energy and a decrease below EF-0.75 eV, i.e. in the region of deep tail states. The effect exhibits a wide spectrum of time constants involved. Based on additional transient surface photo voltage measurements as well as numerical simulations we argue that the observed redistribution of states is not due to a light induced change in surface band bending or due to a mere excitation of electrons from occupied to empty states. Instead, we interpret the observed effect as a conversion of weak to dangling bonds, i.e. a precursor of the Staebler-Wronski Effect, lacking however the final step of hydrogen stabilization necessary for the creation of metastable defects.

Authors with CRIS profile

Jürgen Ristein Lehrstuhl für Laserphysik Lothar Ley Naturwissenschaftliche Fakultät

How to cite

APA:

Ristein, J., & Ley, L. (1993). Signature of the weak bond-dangling bond conversion process in a-Si:H as seen by total photoelectron yield spectroscopy. In MRS Proceedings (pp. 207). Pitsburg: Materials Research Society.

MLA:

Ristein, Jürgen, and Lothar Ley. "Signature of the weak bond-dangling bond conversion process in a-Si:H as seen by total photoelectron yield spectroscopy." Proceedings of the Amorphous Silicon Technology, Pitsburg Materials Research Society, 1993. 207.

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