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Scientific Bulletin. Physical and Mathematical Research

Abstract

This article analyzes the spectrum of the photocurrent in a layered film heterostructure CdTe-ZnSe with deep primesnymi levels. The experimental results demonstrated that the heterostructure CdTe-ZnSe observed a new effect in the measurement of the photoconductivity spectra, depending on the direction of the applied electric field, and the applied field stimulates the emergence of photo-emf. The spectrum of the photocurrent in a layered CdTe- ZnSe heterostructure film with deep impurity levels are considered in the article. It follows from the experimental results that a new effect is observed in the CdTe-ZnSe heterostructure when measuring the photoconductivity spectra depending on the applied direction of the electric field. In this case, the applied field stimulates the appearance of photo-emf. This allows the creation of photosensitive devices with spectral characteristics with fundamentally new features. The structures were prepared using standard thermal vacuum technology by spraying single-crystal ZnSe plates on the surface. CdTe films were synthesized on the surface of ZnSe. CdTe layers on ZnSe grew larger in blocks than, for example, on glass. This is due to the fact that the single crystal ZnSe during the synthesis process has a structure-oriented crystallization. To determine the photosensitivity of a photosensitive film of cadmium telluride doped with silver, spectra are measured in photoconductivity modes with frontal illumination on an IKS-14 monochromator at room temperature, the power was calibrated in absolute units using a thermoelement. In the layers of CdTe, photo-emf arises as if excited by a zone-zone and from deep levels. In this case, virtually all ZnSe luminescence bands are covered. As can be seen from Figure 2, that in this structure the applied field stimulates the appearance of photo-emf. In the region of the absorption edge of CdTe, a large photo-emf occurs, leading to a change in the sign of photoconductivity. This is due to the fact that the applied electric field draws in carriers in the region of asymmetric barriers, which increases the photo-emf. By controlling the effect of barriers on the CdTe surface and on the ZnSe surface, one can get both identical and different signs of photo-emf in two regions of the energy of light quanta equal to 1.4; 1.7 eV and 1.9; 2.3 eV . It is possible that this effect will be perfected to create photodetectors, whose photoresponse sign depends on the wavelength of the light. The created heterostructure is sensitive to ultraviolet light and soft X-rays. In the CdTe-ZnSe heterostructure, a new effect is observed when measuring photoconductivity depending on the direction of the applied electric field. In this case, the applied field stimulates the appearance of photo-emf. This allows the creation of photosensitive devices with spectral characteristics with fundamentally new features.

First Page

15

Last Page

21

References

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