PHOTOCONDUCTIVITY OF A SEMICONDUCTOR WITH A TRANSVERSE GRADIENT OF DRIFT VELOCITY OF CHARGE-CARRIERS

The spectral photosensitivity of a semiconductor with a gradient of th e drift velocity of charge carriers has been investigated. It was foun d to be of either selective or bolometric type depending on mutual dir ections of incident light and of the gradient. Photoconductivity of ge rmanium samples of ringlike geometry was studied experimentally over t he spectral range 0.8-2.2 mum at room temperature. The main results ar e: decay of the photocurrent in a semiconductor where the gradient dif fers from the exponential one and depends on the mutual directions of the gradient and diffusion of carriers; the amplitude of the photocurr ent depends not only on the typical parameters but on light direction and also gradient; determination of both effective lifetime of carrier s and the bandgap by the Moss method is not valid for a semiconductor with a gradient of drift velocity; a photodetector with parameters rev ersibly controlled by an electric field is possible.