The Field and Spectrum Dependences of Impurity Photoconductivity with Exclusion in Compensated Semiconductors

The dependence of impurity photoconductivity on the applied electric field and light wavelength is theoretically studied in structures made of compensated semiconductors with deep centres and non-injecting contacts. The dependence is considered under the conditions that illumination generates current carriers of both signs and that the combined action of light and field causes photostimulated carrier heating by the field resulting in a lesser carrier mobility and a varied capture cross-section by deep levels. A general relationship is obtained between the “excess” concentrations of electrons and holes. It follows from the obtained expression that the exclusion effect is quenched or enhanced depending on the relations between the photoionization cross-sections for generation of electrons and holes, as well as between the concentrations of levels occupied by major carriers and vacant ones. It is shown that in the first case the field dependence of impurity photoconductivity becomes weaker with rising light intensity and even ceases at a certain (critical) value, while in the second case it becomes stronger. A qualitative agreement is also shown between theoretical and experimental data in the case of germanium strongly compensated with antimony and copper impurities. [Russian Text Ignored].

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