Photocarrier dynamics in compensated hydrogenated amorphous silicon

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Abstract
The photocarrier dynamics in compensated a-Si:H is studied using the time-dependent photomodulation technique in the subpicosecond-to-millisecond time range. We find that photocarriers are quickly trapped in shallow impurity levels for t psec, similar to the behavior in singly doped materials. However, their recombination kinetics for t>10 nsec and their steady-state properties are not substantially different from those in undoped materials. This behavior is explained by fast trapping in donor and acceptor states and thermalization into deeper band-tail states which are similar to those in undoped materials.