The Enhancement of Exclusion Effect in Compensated Semiconductors under the Action of Impurity Illumination Generating Minority Current Carriers
Abstract
The influence is studied theoretically of impurity illumination generating minority current carriers on the main characteristics of exclusion in compensated semiconductors with deep centres and non-injecting contacts. The relation between the concentrations of majority and minority carriers is found. The distributions of carriers and field in the base of a n+–n–n+ structure, the depletion layer length, electron and hole lifetimes, and carrier concentrations at the contact depending on light intensity are calculated and analysed, as well as the current-voltage characteristic (CVC). It is found that the exclusion effect gets enhanced under the action of impurity illumination which enhancement is reflected by the fact that the concentration of majority carriers additionally decreases and the field strength rises in the depletion layer, and this results in the possibility of carrier heating by the field causing a decrease in mobility (down to the drift velocity saturation) and an increase in the cross-section of electron capture. This results in an increase in the sublinearity degree of the CVC which may contain, in particular, a region of current saturation. The light intensity is determined at which the electron concentration at the contact becomes equal to zero. It is shown that a qualitative agreement exists between the theoretical and experimental results for n-germanium with antimony impurities exactly compensated by copper. [Russian Text Ignored].