SPACE-CHARGE LIMITED CURRENTS IN ANTHRACENE-CRYSTALS UNDER MODULATED ILLUMINATION

Space charge limited currents have been examined in anthracene crystal s illuminated with a chopped beam of monochromatic light (lambda = 420 nm). The beam was uniformly absorbed in the anthracene crystal. The p rimary objective of our research was to determine mechanisms responsib le for the release and trapping of charge carriers in the case of spac e charge limited currents as a function of time. The experimental resu lts concern the dependences of photocurrents on the frequency of light chopping, light intensity, voltage and current decay after illuminati on. Photocurrent decay as a function of time was exponential for short time periods (i.e. for milliseconds), while for longer periods it was described by the power function t(-1/l), where parameter l is the cha racteristic parameter of the exponential distribution of traps.