Changes of the occupied density of defect states of a-Si:H upon illumination

Journal article

Publication Details

Author(s): Ristein J, Ley L
Journal: Physical Review B
Publisher: American Physical Society
Publication year: 1996
Volume: 53
Journal issue: 8
Pages range: 4522
ISSN: 0163-1829


We study the light-induced transient changes of the near surface density of occupied states g(E) of undoped and boron-doped a-Si:H with photomodulated total photoelectron yield spectroscopy. The data show an increase of g(E) upon illumination between 0.35 eV above E
F and 0.7 eV below E
F (towards the valence band) and a decrease in the region of deep valence-band-tail states. The difference signal depends sublinearly on the laser intensity and reaches a maximum of Δg ≈ 10
17 cm
-3 eV
-1 at a laser intensity of 30 mW cm
-2 (λ=532 nm). Time-resolved measurements reveal rise and decay times of the order of milliseconds. The experimental results are explained quantitatively by a recombination model. In the framework of this model, a range of deep defects around mid-gap energy are singly occupied and neutral at probe-light intensities. Additional illumination with a laser leads to double occupation of these defects and a decrease of the valence-band-tail occupation.

FAU Authors / FAU Editors

Ley, Lothar Prof. Dr.
Naturwissenschaftliche Fakultät
Ristein, Jürgen apl. Prof. Dr.
Lehrstuhl für Laserphysik

Last updated on 2018-09-08 at 05:11