Charge modulation spectra in phosphorus-doped a-Si : H

We discuss models for the infrared spectrum peaked at 0.8 eV reported in vo ltage-modulated optical absorption measurements on a-Si:H based diodes. We associate this spectrum with interface charge modulation of the optical pro perties of the phosphorus-doped a Si:H used as one electrode. We propose th at the spectrum originates with the internal optical transitions of a compl ex incorporating four-fold coordinated phosphorus and a dangling bond. We d iscuss prior evidence against complexing, and suggest further experiments. (C) 2000 Published by Elsevier Science B.V. All rights reserved.