Photoconductivity of Anthracene

The transport properties of current carriers in anthracene have been studied by a crystal counter technique. It has been shown that the charge pulses may be analyzed as the sum of two contributions, a primary component which varies linearly with time and which breaks at a time equal to the transit time, and a secondary component which is caused by slow release of holes from traps in the surface region. Analysis of both components leads to carrier mobilities, thermal dependence of carrier mobilities and of carrier populations, surface trap depths, etc. The interpretation of pulse height vs voltage behavior which is superlinear invokes recombination and/or detrapping processes which are field‐dependent. Experiments are presented which show that recombination at the surface is kinetically more important than recombination in the bulk. It is indicated that the photogeneration of charge carriers at the irradiated surface may be biphotonic.