All sciences. №9, 2023. International Scientific Journal - страница 3

Ключевые слова: фотопроводимость, фото-ЭДС, спектральное распределение фоточувствительности, ток короткого замыкания, асимметрия барьеров, поверхностная фото-ЭДС, глубокие уровни, примесная фотопроводимость, коронный разряд.

The development of micro – nano electronics and new technological possibilities for the manufacture of complex semiconductor structures stimulate further study of new optical and photovoltaic phenomena in active film elements.

Currently, oxides and nitrides of semiconductors and semiconductor films grown on their surfaces are widely used in the manufacture of multichannel photovoltaic converters and other active elements of microelectronics circuits, and in particular, optoelectronics. In this case, it is possible to obtain high-quality and dielectric layers of semiconductors with deep levels. At the same time, it is easier and cheaper to use polycrystalline films sprayed on amorphous substrates rather than epitaxial ones.

CdTe semiconductor films are an important material for the creation of photodetector devices based on heterostructures operating in the near (up to 3 microns) and far (8—14 microns) The IR range. It is of interest to obtain heterostructures based on photosensitive layers with different types of conductivity. A promising p-type material doped with silver and copper, which give an acceptor level in the forbidden zone with a long lifetime of non-main charge carriers [1—14].

The aim of the work is to study new photovoltaic properties of active CdTe thin films and heterostructures in a system with SiO2-Si under conditions of specific external influences.

The results of experimental studies of the photovoltaic properties of textures from sprayed layers of CdTe – SiO2 – Si, etc., allow the development of new devices based on polycrystalline films with controlled properties.

Below we investigate the photosensitivity of the CdTe – SiO2 – Si structure, which can be used, for example, as a metal – silicon nitride oxide semiconductor (MNP) – a transistor with a polarized dielectric [1,2], which allows electrical rewriting of information.

Polycrystalline (grain sizes are 0.05—0.1 microns) CdTe films were obtained on the surface of SiO2 – Si. CdTe and Ag and Cu impurities evaporated in a vacuum of 10—5 mmHg from separate evaporators onto the heated oxidized surface of Si. The relative arrangement of the layers of the CdTe – SiO2 – Si structure and the ohmic contacts to them is schematically shown in Fig.1. In such a structure, photosensitivity is controlled by external influences, such as an electric field or corona discharge, which change the built-in field in the dielectric. In this case, we have a «reverse» field – effect transistor of the CdTe – SiO2 – Si type, when the control charge is located under the semiconductor layer, and its surface remains open.

Fig.1 The relative position of the layers of the CdTe – SiO2 – Si structure. 1,2 – contacts; 3 – filtering contacts.

Currently, electrification using a corona discharge is the main method of sensitizing photovoltaic layers in industrial electrography [3].

An experimental setup was used for corona electrification of the studied structures, the block diagram of which is presented in [4]. Electrification occurs due to deposition of positive or negative ions in a corona discharge on the surface of the layer. Corona discharge occurs if the voltage between the metallized surface of the Al layer and the electrode exceeds 6 kV, when the field embedded in the structure reached 100 V. The spectra of the short – circuit current charged in this way in the CdTe – SiO2 – Si structure were studied depending on the magnitude of the external corona discharge and showed that in the static mode a shift of the spectra to the short-wave region is observed (Fig.2). It turned out that in such a structure, the photosensitivity of the layer can be controlled by the action of an external corona discharge potential (using the «field effect» method), which, as it turns out below, induce embedded electric charges in the dielectric.