Mercury cadmium telluride (Hg1_xCdxTe) is widely utilized for infrared detection applications. However, the quality of the surface and the presence of interface defects significantly impact device performance, so further improvements in surface passivation are still necessary. In this study, we explore the use of plasma-enhanced atomic layer deposition (PE-ALD) to deposit HfO2 as a passivation layer for HgCdTe in the temperature range of 80-160 degrees C. The insulating film, semiconductor surface, and their interface are characterized using spectral ellipsometry, X-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS), atomic force microscopy (AFM), electron microscopy, and capacitance-voltage (C-V) methods. XPS analysis reveals that the fraction of impurities in the HfO2 films significantly decreases at higher deposition temperatures. Simultaneously, changes in the surface composition of HgCdTe become more pronounced. The bandgap width of HfO2 and the insulator-semiconductor interfacial band discontinuity are estimated using EELS and XPS. The surface morphology of the deposited coatings closely resembles that of the underlying HgCdTe. The permittivity of the insulator and the effective fixed charge strongly depend on the deposition temperature. Our findings demonstrate that low-temperature PE-ALD HfO2 effectively passivates the HgCdTe surface, and we propose an optimal deposition temperature for the further development of HgCdTe-based devices.

A strong response of nanosystems to the action of weak microwave power through the gap between the sample and the end of the coaxial cable from the microwave generator is detected by measurements at 4.2 K of the conductance of a short-channel p -type silicon transistor and samples with a short quantum point contact in a two-dimensional electron gas of GaAs/AlGaAs heterostructures. The conductance response is gigantic in the tunnel mode of the devices, and the sign of the microwave photoconductance outside this mode depended on the mesoscopic state of the sample and the studied range of gate voltage. The nature of the discovered effects is elucidated by modeling mesoscopic transport within the framework of single-particle quantum mechanics and the Landauer formula as well as by analyzing the basic circuits of electrical control of the semiconductor device. The main reason for the response of nanosystems to microwave exposure is forced in-phase charge oscillations in contacts to the semiconductor due to capacitive coupling in the near metallic environment of the sample.

Quantum point contacts with a short (100-nm) channel in a high-mobility two-dimensional electron gas of GaAs/Al(Ga)As heterostructures and a short-channel p-type field-effect transistor in a silicon-on-insulator structure were fabricated and studied experimentally and by modeling at the Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia, in order to study the response of the samples to weak irradiation by an electromagnetic field with a frequency of 2 GHz. This response in the tunneling mode at a temperature of 4.2 K turned out to be giant and was observed against the background of features caused by impurity disorder.

Two-subband magnetotransport of quasi-2D electron gas in GaAs single quantum well with AlAs/GaAs superlattice doping has been studied at T = 4.2 K in magnetic fields B < 2T. It was demonstrated that application of negative gate voltage leads to transformation of studied two-subband electron system into the one-subband system. This transformation is accompanied by appearance of positive magnetoresistance. This behavior has been described by conventional model of classical positive magnetoresistance that takes into account elastic intersubband scattering of electrons. Combined analysis of classical positive magnetoresistance and quantum magneto-intersubband oscillations makes it possible to define the values of transport rates of intrasubband scattering and quantum rate of intersubband scattering.

The 15-μm-pitch 640×512 FPA detectors with a long-wavelength sensitivity limit of 5.1 μm based on MCT layers grown by molecular-beam epitaxy on Si substrates were designed and fabricated. Both electrical circuit and topology of a 15-μm-pitch 640×512 ROIC for such FPAs were developed, according to which multiplexers ensuring operation of manufactured FPAs at a clock frequency of up to 20 MHz were fabricated. Using the flip-chip method on In bumps, hybrid 640×512 MCT-based FPA detectors with 15-μm pixel pitch were obtained. The best fabricated FPA detectors were found to have the following characteristics: mean NETD value < 18 mK and number of non-defective pixels > 99.8%.

The influence of illumination on a high mobility two-dimensional electron gas with high concentration of charge carriers is studied in selectively doped single GaAs quantum wells with short-period AlAs/GaAs superlattice barriers at a temperature T = 4.2 K in magnetic fields B < 2 T. It is shown that illumination at low temperatures in the studied heterostructures leads to an increase in the concentration, mobility, and quantum lifetime of electrons. An increase in the quantum lifetime due to illumination of single GaAs quantum wells with modulated superlattice doping is explained by a decrease in the effective concentration of remote ionized donors.

Impact of illumination on high-mobility dense 2D electron gas in selectively doped single GaAs quantum well with short-period AlAs/GaAs superlattice barriers at T=4.2 K in magnetic fields B<2 T has been studied. It was demonstrated that illumination at low temperatures gives rise to enhancement of electron density, mobility and quantum lifetime in studied heterostructures. The enhancement of quantum lifetime after illumination for single GaAs quantum well with modulated superlattice doping had been explained as consequence of decrease in effective concentration of remote ionized donors. Keywords: persistent photoconductivity, quantum lifetime, anisotropic mobility, superlattice barriers.

Impact of illumination on high-mobility dense 2D electron gas in selectively doped single GaAs quantum well with short-period AlAs/GaAs superlattice barriers at T = 4.2 K in magnetic fields B < 2 T has been studied. It was demonstrated that illumination at low temperatures gives rise to enhancement of electron density, mobility and quantum lifetime in studied heterostructures. The enhancement of quantum lifetime after illumination for single GaAs quantum well with modulated superlattice doping had been explained as consequence of decrease in effective concentration of remote ionized donors.

Temperature remote diagnostics systems of industrial electrical installations based on bolometric photodetectors are studied. Photoreceiving forward looking infrared thermal imagers and a specialized radiometric thermal imager with internal temperature sensors and calibration shutters are considered. The best coating for calibration shutters with a minimum reflection of IR radiation from their surface is determined (the integral reflection coefficient in the spectral range of 8–14 μ m is no more than 5.8

Matrix photosensitive elements based on a HgCdTe semiconductor solid solution on silicon substrates with 640 × 512 elements at a pitch of 25 μm with a long-wavelength sensitivity of 5 μm at half maximum are designed and produced. The scheme and topology are developed according to which matrix multiplexers with 640 × 512 elements at a pitch of 25 μm, which ensure operating modes at a clock frequency up to 10 MHz, are manufactured. Using a hybrid assembly method on indium bumps, a matrix photodetector with 640 × 512 elements at a pitch of 25 μm is produced. The best photodetector specimens are characterized by the following parameters: average NETD value <13 mK and the number of workable elements > 99.5%.

AbstractGrowth-related structural defects present on the surface of InAlAs layers grown by molecular beam epitaxy on InP(001) substrates influence the temperature dependences of the current–voltage characteristics of Au/Ti/InAlAs Schottky barriers. It is established that these defects in the form of pits cause the appearance of regions with reduced barrier height. At a surface density of ≥10^7 cm^–2, these defects significantly influence the parameters of the Schottky barriers at temperatures below 200 K.

The effect of microwave radiation on low-temperature electron magnetotransport in a square antidot lattice with a period of d ≈ 0.8 µm based on a GaAs quantum well with two occupied energy subbands E1 and E2 is investigated. It is shown that, owing to a significant difference between the electron densities in the subbands, commensurability oscillations of the resistance in the investigated antidot lattice are observed only for the first subband. It is found that microwave irradiation under the cyclotron resonance condition results in the formation of resistance oscillations periodic in the inverse magnetic field in the region of the main commensurability peak. It is established that the period of these oscillations corresponds to the period of magneto-intersubband oscillations. The observed effect is explained by the increase in the rate of intersubband scattering caused by the difference between the electron heating in the subbands E1 and E2.

Low-temperature magnetotransport in a quasi-two-dimensional electron system based on a selectively doped GaAs quantum well with two occupied quantum-confinement subbands with one-dimensional periodic modulation of a potential is investigated. It is shown that commensurability oscillations of the resistance in this electron system coexist with magneto-intersubband oscillations. It is found that, in addition to commen-surability oscillations, the one-dimensional periodic potential in the two-subband electron system leads to the modulation of the magneto-intersubband oscillation amplitude. The experimental results are explained by the formation of Landau bands in the quasi-two-dimensional electron system with one-dimensional periodic modulation of the potential.

Electron transport in single GaAs quantum wells of widths from 22 to 46 nm with two populated quantum-confinement subbands ES and EAS is investigated at a temperature of T = 4.2 K in tilted magnetic fields B < 2 T. The angle α between the applied magnetic field and the normal to the plane of the structure under study is varied from 0° to 90°. In a perpendicular magnetic field (α = 0), magnetointersubband oscillations with a period determined by the relation ΔSAS = EAS - ES = jħωc, where ωc is the cyclotron frequency and j is a positive integer, are observed in all investigated quantum wells. In tilted fields, the peaks of magnetointersubband oscillations are shifted toward higher fields B cos α. This shift is explained by an increase in the energy splitting ΔSAS with increasing component B sin α. In 46- and 36-nm-wide quantum wells, beats of magnetointersubband oscillations are observed at angles α > 72° and α > 85°, respectively. The origin of this unexpected behavior of magnetointersubband oscillations in tilted magnetic fields is discussed.

Growth-related structural defects present on the surface of InAlAs layers grown by molecular beam epitaxy on InP(001) substrates influence the temperature dependences of the current–voltage characteristics of Au/Ti/InAlAs Schottky barriers. It is established that these defects in the form of pits cause the appearance of regions with reduced barrier height. At a surface density of ≥10 7 cm –2 , these defects significantly influence the parameters of the Schottky barriers at temperatures below 200 K.

In this article, we present an overview of a focal plane array (FPA) with 640 512 pixels based on the AlGaAs quantum well infrared photodetector (QWIP). The physical principles of the QWIP operation and their parameters for the spectral range of 8–10 μm have been discussed. The technology of the manufacturing FPA based on the QWIP structures with the pixels 384 288 and 640 512 has been demonstrated. The parameters of the manufactured 640 512 FPA with a step of 20 μm have been given. At the operating temperature of 72 K, the temperature resolution of QWIP focal plane arrays is less than 35 mK. The number of defective elements in the matrix does not exceed 0.5%. The stability and uniformity of the FPA have been demonstrated.

This paper describes the design of readout integrated circuits (ROICs) for hybrid infrared focal plane arrays (IR FPAs). This work contains the estimation of the noise equivalent temperature difference (NETD) of IR FPAs based on frame and row integration of pixel signals in the spectral ranges of 8 to 14 and 3 to 5 μm. This paper also describes the development of ROICs for IR FPAs created with the use of mercury—cadmium—telluride (MCT) photodiodes and quantum well infrared photodetectors (QWIPs). The designed ROICs ensure the use of matrix and linear photodetector chips, including those with increased dark currents, in order to produce IR FPAs with temperature resolution corresponding to the world level of array analogs.