Abstract
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 ${\mathit{E}}_{\mathit{F}}$ and 0.7 eV below ${\mathit{E}}_{\mathit{F}}$ (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 \ensuremath{\Delta}g\ensuremath{\approxeq}${10}^{17}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ ${\mathrm{eV}}^{\mathrm{\ensuremath{-}}1}$ at a laser intensity of 30 mW ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ (\ensuremath{\lambda}=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. \textcopyright{} 1996 The American Physical Society.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.