SOME ASPECTS OF THE ROLE OF HOLES IN THE TRANSIENT-RESPONSE OF A-SI-HPIN-DIODES

We model the transient response of a-Si:H pin-diodes and focus on the behaviour of the photocurrent after switch-on or off of steady illumin ation. The distinct experimental features such as an overshoot of the photocurrent after switch-on are reproduced in the simulation. The rea son for the overshoot is identified as a change over from recombinatio n at the contacts to recombination with the opposite carrier via dangl ing bonds. This occurs with some delay so that the electron density re aches a quasi-steady state value which is then reduced at later times and in the steady state. The response of holes for both illumination t hrough the n- or p-side of the diode is shown to determine the respons e time of the total current for low defect diodes.