Investigation of Photoelectric Converters with a Base Cadmium Telluride Layer with a Decrease in Its Thickness for Tandem and Two-sided Sensitive Instrument Structures

Photovoltaic cells with a base layer of cadmium telluride with a decrease in its thickness are studied. It is known that the widespread use of photovoltaic converters is constrained by their high price in the case of highly efficient instrument structures, or low efficiency. The creation of tandem and two-sided sensitive photoelectric converters will reduce their cost while increasing their efficiency. However, to create tandem and two-sided sensitive photoelectric converters, the necessary conditions are the use of transparent contacts and a decrease in the thickness of the base layer for efficient absorption of incident radiation by the converter, which is lower. In the research process, it was found that reducing the thickness of the base layer to 1 μm allows to increase the efficiency of the photoelectric transducer during irradiation from the back. An increase in the efficiency of the photoelectric converter occurs due to a decrease in the distance from the generation region of nonequilibrium charge carriers in the region of separation. If the thickness of the base layer is less than 1 μm, then regardless of which side of the irradiation is carried out, a decrease in the efficiency of the instrument structure is observed. Increase in the efficiency of photoconverters is associated with an increase in the negative influence of recombination processes on the back contact, a decrease in the number of charge carriers generated due to incomplete absorption of incident radiation, and a decrease in the volume of the built-in field of the separating barrier when it overlaps with the depletion region of the back contact. ITO/CdS/CdTe/Cu/ITO SCs with a base layer thickness of 1 μm demonstrates degradation stability. The highest value of efficiency in the case of illumination from the front side 8.1 % and with illumination from the back side 3.8 % received after a year of operation of the photovoltaic converter

Field Effect Transistors for Terahertz Detection: Physics and First Imaging Applications

Resonant frequencies of the two-dimensional plasma in FETs increase with the reduction of the channel dimensions and can reach the THz range for sub-micron gate lengths. Nonlinear properties of the electron plasma in the transistor channel can be used for the detection and mixing of THz frequencies. At cryogenic temperatures resonant and gate voltage tunable detection related to plasma waves resonances, is observed. At room temperature, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector. We present the main theoretical and experimental results on THz detection by FETs in the context of their possible application for THz imaging.Comment: 22 pages, 12 figures, review pape

Terahertz-photon-modified magnetotransport in a semiconductor in Voigt geometry

We present a theoretical study of transport and optical properties of a semiconductor-based electron gas subjected simultaneously to quantizing magnetic fields and intense terahertz THz laser fields in Voigt geometry. It is found that the presence of the THz radiation can result in an enhanced magnetophonon resonance effect and a resonant-absorption peak can be observed at about f1 THz for GaAs in high magnetic fields. The results are pertinent to experiments where THz free-electron lasers are employed as intense radiation sources

Comparison Studies of Infrared Phototransistors with a Quantum-Well and a Quantum-Wire Base

Infrared phototransistors based respectively on a quantum-well and a quantum-wire structures, utilizing intersubband electron transitions, are considered using developed analytical model. The dark currents and responsivities of the phototransistors in question are compared. It is shown that the quantum-wire infrared phototransistor can surpass the infrared phototransistor with a quantum well in performance especially at low temperatures. This is due to the one-dimensional nature of the electrons in the quantum-wires providing higher energy of thermal excitation, leading to low dark current and sensitivity to normal incident radiation