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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 99.5%.

The requirements imposed on vertical-cavity surface-emitting lasers in a number of metrological problems in which optical pumping of alkali atoms is used are considered. For lasers produced by different manufacturers, these requirements are compared with the experimentally observed spectral characteristics at a constant pump current and in the microwave modulation mode. It is shown that a comparatively small number of lasers in the microwave modulation mode make it possible to obtain the spectrum required for atomic clocks based on the coherent population-trapping effect.

In a temperature range of 9–200 K, temperature dependences of the differential resistance of space-charge region in the strong inversion mode are experimentally studied for MIS structures based on CdxHg1–xTe (x = 0.22–0.40) grown by molecular-beam epitaxy. The effect of various parameters of structures: the working layer composition, the type of a substrate, the type of insulator coating, and the presence of a near-surface graded-gap layer on the value of the product of differential resistance by the area is studied. It is shown that the values of the product RSCRA for MIS structures based on n-CdHgTe grown on a Si(013) substrate are smaller than those for structures based on the material grown on a GaAs(013) substrate. The values of the product RSCRA for MIS structures based on p-CdHgTe grown on a Si(013) substrate are comparable with the value of the analogous parameter for MIS structures based on p-CdHgTe grown on a GaAs(013) substrate.

A photodetector array chip for detection of the optical signal in a wave range of 0.4–1.0 μm; conversion of the optical signal into the electric signal; and its extraction in the analog form to 1, 2, 4, 8, or 16 outputs has been designed, fabricated, and studied. The main parameters of this chip are the following: the charge capacity is up to 200000 electrons, the frame rate is higher than 600 Hz at the maximum resolution, and the integrated sensitivity is up to 1000 V/(lx s).

Metal–insulator–semiconductor structures based on n -Hg 1− x Cd x Te ( x = 0.19–0.25) were grown by molecular-beam epitaxy on the GaAs (0 1 3) substrates. Near-surface graded-gap layers with high CdTe content were formed on both sides of the epitaxial HgCdTe. Admittance of these structures was studied experimentally in a wide temperature range (8–150) K. It is shown that an increase in the composition of the working layer and a decrease in temperature lead to a decrease in the frequency of transition to high-frequency behavior of the capacitance–voltage characteristics. The differential resistance of space charge region in the strong inversion increases with the composition of the working layer and for x = 0.22 and 0.25, the differential resistance is limited by the Shockley-Read generation. The values of the differential resistance of space charge region at different frequencies and temperatures were found.

The characteristics of SWIR (1.6–3 μm) 320 × 256 and 1024 × 1024 focal plane arrays (FPA’s) based on n-type In-doped HgCdTe heteroepitaxial layers are reported. The HgCdTe layers were grown by molecular beam epitaxy on silicon substrates with ZnTe and CdTe buffer layers. p–n junctions were formed by arsenic ion implantation into HgCdTe film. Reverse current in the temperature range from 210 to 330 K was found to be limited by the diffusion mechanism. At the same time in the temperature range from 140 to 210 K the reverse current was dominated by the thermal generation of charge carriers through deep traps located in the middle of the band gap. At 170 K NETD was less than 40 mK.

Total conductance of MIS structures based on graded-gap p-Hg1–хCdхTe (x =0.22–0.23) grown by molecular beam epitaxy (MBE) is studied in a wide temperature range 8-300 K. It is found that for MIS structures based on graded-gap MBE p-Hg1–хCdхTe (x =0.23) doped with As to a concentration of 1017 сm–3, the differential resistance of space charge region in the temperature range 8–100 K is limited by the processes of tunnel generation of minority carriers. It is shown that for MIS structures based on graded-gap MBE p-Hg1–хCdхTe (x =0.22) with the hole concentration of (8–9)·1015 сm–3, the differential resistance of space charge region in the temperature range 30–90 K is limited by the processes of Shockley-Read generation, regardless of the presence of a graded-gap layer. At higher temperatures, the differential resistance of space-charge region is limited by processes of the minority carrier diffusion from the quasi-neutral bulk region.

3 Admittance of MIS structures based on graded-gap n-Hg1-хCdхTe (x = 0.31-0.32) grown by molecular beam epitaxy (MBE) is investigated in a wide temperature range (8-300 K). It is shown that the temperature and frequency dependences of the differential resistance of space charge region for structures with a graded-gap layer are qualitatively similar to those for structures without a graded-gap layer. It is found that for MIS structures based on MBE n-Hg1-хCdхTe (x = 0.31-0.32), regardless of the presence of a graded-gap layer, the differential resistance of space charge region is limited by the processes of Shockley-Read generation in the temperature range of 25-100 K.

Total conductance of MIS structures based on heteroepitaxial n-Hg1–xCdxTe (x = 0.23) grown by molecular beam epitaxy has been studied in the temperature range 8–150 K at frequencies of alternating test signal 2 kHz – 2 MHz. It is found that for structures with a near-surface graded-gap layer and an increased content of CdTe, the differential resistance of space charge region increases significantly, as the temperature decreases from 77 to 8 K, and for structures without a graded-gap layer, the changes in the differential resistance of space charge region are nonmonotonic and relatively small. These results can be explained by the fact that at 8–77 K, for structures without graded-gap layers, the differential resistance of the space charge region is limited by tunneling via deep levels, and for structures with graded-gap layers, it is limited by the Shockley-Read generation processes.

This paper gives the parameters of 320 × 256 element long-wavelength infrared photodetectors fabricated by a new improved technology based on heteroepitaxial mercury-cadmium-tellur structures. In these photodetectors, the variation of the photodiode bias voltage over the area of the array is minimized; inefficient photodiode regions related to both hybridization and spike-shaped growth defects of epitaxial films are eliminated; the current-voltage characteristics of the diodes in the resulting photodetectors are homogeneous and are limited by the diffusion current component up to −400 mV. The dark current is 0.25–0.45 nA, and R 0 A = (0.6–3) · 102 Ω · cm2. The voltage sensitivity, the threshold irradiance, and the average NETD at the maximum sensitivity are 11.8 · 108 V/W, 3.7 · 10−8 W/cm2, and 26.8 mK, respectively. The percentage of defective elements is 1.5%.

Results of the research aimed at improving the strength of hybrid photodetectors (PD) based on mercury-cadmium-telluride heteroepitaxial layers are presented. It is shown that annealing of silicon multiplexers at 157 °C in a hydrogen flow in vacuum changes the shape of indium bumps to hemispherical and levels off their mechanical properties over the plate. Controlled recovery of the natural curvature of silicon multiplexer plates and photosensitive element arrays in hybrid photodetectors at 120 °C extends their operation time. A sequence of technological operations on PD hybridization providing an increase in the efforts needed for separating photosensitive elements from silicon multiplexers at least by 75% compared to the PD with fused indium bumps is proposed.

The dependences of photo-emf of metal-insular-semiconductor structures based on n-Hg1–xCdxTe (x = 0.21–0.23) on bias voltage, frequency, and temperature are experimentally studied. The photoelectrical characteristics of the metal-insulator-semiconductor structures based on epitaxial n-Hg1–xCdxTe (x = 0.21–0.23), including those taking into account the presence of near-surface graded-gap layers having an increased content of CdTe at various temperatures are calculated. The calculated dependences are compared with experiment and it is shown that the differential resistance of the spatial charge region for the metal-insulatorsemiconductor structures based on n-Hg1–xCdxTe (x = 0.21–0.23) without a graded-gap layer is restricted by tunneling through deep levels, whereas the differential resistance of the same structures with graded-gap layers – by the charge-carrier diffusion.

Capacitance-voltage characteristics of MIS structures based on graded band-gap heteroepitaxial HgCdTe (x = 0.22–0.23 and 0.32–0.36) with grown in situ CdTe as a passivating coating are examined. The average surface-state densities as well as mobile- and fixed-charge densities are determined for the HgCdTe/CdTe, HgCdTe/CdTe–SiO2–Si3N4, and HgCdTe/CdTe–ZnTe systems. It is shown that grown in situ CdTe forms a fairly qualitative interface, and deposition of additional SiO2–Si3N4 and ZnTe layers makes it possible to control the electric strength and charges in the dielectric used.

Short-cavity diode lasers (SCDLs) emitting at the 894-nm D1 line of caesium are developed. Low threshold currents and power consumption will make it possible to use these lasers in chip-size atomic clocks (CSACs) and magnetometers. The SCDL parameters are comparable with the parameters of surface-emitting lasers.

The effect of an external magnetic field on the dark current of photodiodes in far-IR matrix photodetector arrays fabricated by boron ion implantation into heteroepitaxial cadmium mercury telluride (CMT) layers has been studied. A new method is proposed for separately determining the lateral and normal dark current components in CMT photodiodes of the matrix photodetectors. It is established that the dark current of these photodiodes (at 77 K) with dimensions comparable with the minority carrier diffusion length is determined primarily by the lateral component.

Voltage, frequency, and temperature dependences of photo-emf are experimentally studied in the MIS HgCdTe/SiO 2 /Si 3 N 4 and HgCdTe/AOF structures. The MIS structures were produced on the basis of graded-bandgap Hg 1−x Cd x Te films grown by molecular-beam epitaxy on GaAs substrates. It is found that the subsurface graded-band-gap layers do affect the photoelectrical characteristics of MIS structures. The mechanisms limiting the differential resistance in the space-charge region at various temperatures are revealed.

The first results on the formation of n+-p photodiodes with a long-wavelength boundary at λ0.5 = 10.6 μm based on p-CdHgTe epilayers with a hole density of 3.3 × 1014 cm−3 are presented. The CdHgTe layers were obtained by molecular beam epitaxy and exhibited p-type conduction in the as-grown state. The hole density and mobility were determined by means of the mobility spectrum technique. The photodiode structures were prepared by B+ ion implantation into as-grown p-CdHgTe epilayers without additional annealing. The R0A product for the n+-p photodiodes obtained is about 20 Θ cm2 at 77 K.

The voltage dependence of photo-emf in the HgCdTe/SiO 2 /Si 3 N 4 and HgCdTe/AOF MIS structures is experimentally studied. The heteroepitaxial graded-band films Hg 0.78 Cd 0.22 Te were produced on the GaAs substrates by molecular-beam epitaxy. It was found that the type of field dependence of photo-emf is related to the conduction type of the semiconductor used and to the presence of near-surface graded-band layers.

A possibility of application of semiconductor lasers of the visible range as exciting sources for Raman spectroscopy is studied. An experimental set-up for measuring Raman spectra of polycrystalline dielectrics and broad-gap semiconductors excited by a semiconductor laser with a wavelength of 640 nm was created. The conditions under which the spectral width of the lasing line of a semiconductor laser was within 10-3 cm-1 in the continuous mode with a power of 10 mW are realized. The characteristics of various types of exciting sources used in Raman spectroscopy are compared. The results of studies of the characteristic Raman spectra excited with a semiconductor laser in polycrystalline sulfur are presented.

The study of the photosensitivity of an In-SiO2-Cd0.28Hg0.72Te metal-insulator-semiconductor structure with an opaque electrode is continued and the results are reported in this paper. The effect of a drastic decrease in photosensitivity with increasing inversion voltage is considered. This effect manifests itself both under unmodulated illumination (measurements of photocapacitance) and under modulated illumination (measurements of photovoltage), with the onset of a decrease in photovoltage coming ahead of that in photocapacitance. It is believed that this effect is caused by an increase in the longitudinal resistance of the inversion layer and by the anomalous generation of charge carriers at the semiconductor-insulator interface; as a result of the latter, the resistance of the induced p-n junction decreases.

It is demonstrated for the first time that high-performance scanning infrared (IR) focal plane assemblies of the 288 × 4 format for long-wavelength (8–12 μm) IR spectral range can be created based on a CdxHg1 − xTe/Si(310) heterostructure.

A technology has been elaborated and photodetector modules based on Hg1−x CdxTe/GaAs heterostructures and GaAs/AlGaAs multiquantum-well structures grown by molecular-beam epitaxy were fabricated for the 3–5 and 8–12 µm spectral ranges. The photosensitive HgCdTe layers were grown on the GaAs substrates with the intermediate buffer layer of CdZnTe. To decrease the surface effect on the recombination processes, the graded-gap Hg1−x CdxTe layers with x increasing towards the surface were grown. A silicon multiplexer was designed and fabricated by CMOS/CCD technology with a frame rate of 50 Hz. The hybrid microassembly of the photodetector array and the multiplexer was produced by group cold welding on indium columns while monitoring the connection process. The fabricated 128×128 modules based on HgCdTe layers with the cutoff wavelengths 6 and 8.7 µm had a temperature resolution of 0.02 K and 0.032 K, respectively, at a temperature of 78 K and a frame rate of 50 Hz. The photosensitive GaAs/AlGaAs multilayer quantum well structures were fabricated by MBE. It is shown that the technology developed allows 128×128 multielement photodetector arrays (λpeak=8 µm) to be produced with a temperature resolution of 0.021 K and 0.06 K at operating temperatures of 54 K and 65 K, respectively.

It is shown that dark currents measured at 77 K in Hg1−xCdxTe (x⋍0.21) homojunctions can be adequately described by the balance equations with allowance made for the two main charge-transport mechanisms, i.e., tunneling assisted by traps in the band gap and recombination via these traps; the above homojunction may find application in microphotoelectronics in the infrared spectral range of 8–12 µm. Other charge-transport mechanisms are included in the consideration as additive terms. A comparison between the experimental current-voltage characteristics and dynamic resistance of HgCdTe diodes with the results of calculations was carried out. A good agreement was obtained between experimental data and the results of calculations, in which the donor and acceptor concentrations in the n and p regions of diodes, the concentration of traps and the position of their levels in the band gap, and the lifetimes of charge carriers for recombination via these traps were used as adjustable parameters.

The characteristics of the photodiodes based on CdxHg1−xTe solid solutions with graded gap layers were calculated in the context of a one-dimensional diffusion-drift model. The parameters of the photodiodes were shown to be improved when the p-n junction was located in the near-surface graded gap region rather than in the central homogeneous section of the structure. The photodiodes with the n-type layer adjacent to the substrate were found to offer an advantage over the diodes with the p-layer close to the substrate in the case of illumination from the substrate side.

This paper is the continuation of the analysis of a method of determining the cutoff wavelength λc of infrared photodetectors by irradiating the sample with radiation from two blackbodies with different temperatures. The emitters can operate at lower temperatures as the cutoff wavelength λc is increased. The parameters of a system employing two blackbodies, which are placed inside a liquid-nitrogen cryostat and have temperatures of 260 and 320 K, respectively, are presented. It is shown that an error of 1 K in determining the lower or higher temperature produces an error of approximately 0.3 and 0.2 µm, respectively, in λc if λc=10 µm. Measurements on photodiodes fabricated on the basis of Cd0.24Hg0.76Te (λc=8.1 µm) epitaxial layers showed that the difference in the values of λc obtained by this method and from spectral measurements is no more than several tenths of a micron. It is suggested that this method be used as a standard method.

A method is proposed for improving the measurement accuracy of multichannel optoelectronic instruments in mechanical engineering. The method involves the suppression of crosstalk and processing of the measurement data in accordance with the resulting transfer function of the detector. An example of practical implementation is given.

This paper reports on the realization of small area long-wavelength infrared (LWIR) photodiodes based on CdHgTe films grown by molecular beam epitaxy (MBE). The composition of the ternary compound is controlled in situ by a single-wave ellipsometer that offers the possibility to grow epilayers with a desirable composition profile across the film thickness. Photodiodes have a vertical configuration and have been fabricated using planar technology by annealing under an anodic oxide film.

All-round studies of heteroepitaxial HgCdTe nanostructures (NS) growth on GaAs and Si substrates by molecular beam epitaxy have been carried out. In case of Si substrate HgCdTe NS's is very perspectives for IR detectors because of equal thermal expention coefficient with silicon read-out circuits. The problems of HgCdTe conjugations with Si at epitaxy connected with large differences in lattice mismatch and differences in chemical bonding that leads to antiphased domains. We found that the precise formation of transition layer (2 nm in thickness between Si substrates and first ZnTe buffer layer leads to growth HgCdTe NS's without antiphrasis domains. V-defects and etch pits densities are equal to 103 cm−2 and 107 cm−2 respectively. The HgCdTe/Si were used for fabrication photovoltaic 640×512 MWIR focal plane arrays. The operability for λ1/2 = 4.2 μm (77K) was over 97%. The response (Sv) and NETD were as 1,5 × 109 V/W and less 20 mK respectively. We developed the precise growth of symmetric and antisymmetric HgTe QW. We found the following effects: the presence 2D electron gas with high mobilities over 5×105 cm/V×s in doped HgTe QW, the presence @D holes and electrons in undoped HgTe QW and high sensitivity to linear and circular polarized IR and THz radiation in 6 – 400 μm region.

This paper proposes a photodetector design based on a CdHgTe variband heteroepitaxial structure with a high-conductivity layer (HCL) that ensures that the photodiodes have low series resistance and simultaneously serves the function of a short-wavelength cutoff filter. Based on an analysis of how the parameters of the HCL affect the quantum efficiency and the noise-equivalent temperature difference of the photodetector arrays (PDAs), its optimum parameters are determined. Samples of PDAs are fabricated with a format of 320×256 elements for the 8-12-μm spectral range, based on hybrid assembly of photosensitive elements made from p-type (013) HgCdTe/CdTe/ZnTe/GaAs heteroepitaxial structures with an HCL and a silicon multiplexer. The voltage sensitivity, the threshold irradiance, and the noise-equivalent temperature difference at the maximum sensitivity were 4.1×108V/W, 1.02×10−7W/cm2, and 27mK, respectively.

Infrared n-p-photodiode photodetectors based on a hybrid assembly of photosensitive elements of format 288×4 with a 56×43-μm step, made from mercury-cadmium telluride heteroepitaxial structures obtained by molecular-beam epitaxy, have been developed, fabricated, and investigated for the 8–12-μm spectral range, along with silicon multiplexers with bidirectional scanning and internal time delay and storage of the signal. The 288×4-format linear photodetector has the following mean values of voltage sensitivity, detectivity, and NETD at the maximum sensitivity: (1–3)×108V∕W, (1.5–2.0)×1011cmHz1∕2W−1, and 9mK, respectively. There are no defective channels.

This paper presents a comparison of the dark currents and differential resistance of photodiodes, obtained using p-type cadmium-mercury telluride (CdHgTe) layers doped with boron ions, grown by molecular-beam epitaxy (MBE) and liquid-phase epitaxy (LPE). The volt-ampere responses for diodes on CdHgTe layers with composition x=0.215, grown by MBE and LPE (x≈0.222) are characterized by various saturation currents (reverse bias −0.25V) of 1-2 and 5-10nA, even though the band gap is greater for the latter. In this case, the maximum differential resistance is 4×109 and 5×107Ω for diodes based on MBE and LPE layers, respectively. The experimental data are compared with the calculated values. Numerical modelling showed that, for MBE structures with low biases, the dark current is limited by the diffusion current and by the Shockley-Read-Hall current outside the n-p junction, whereas, in LPE structures, there is a substantial contribution of currents through traps in the depletion region.

This paper discusses the results of investigations of processes for forming monolithic integrated cadmium-mercury telluride (CdHgTe)-based IR arrays and their parameters. The processes for growing CdHgTe heteroepitaxial layers (HELs) by molecular-beam epitaxy (MBE) in the cells of a silicon multiplexer have been studied, as well as for forming an n-p junction and contact compounds. For the selective growth of CdHgTe MBE HELs, regimes have been determined for preparing a silicon surface in dielectric windows with dimensions from 30×30to100×100μm. Selective layers of CdHgTe (8μm)/CdTe(5-7μm)/ZnTe(0.02μm) have been grown on Si (310). Ion implantation of boron into selective p-type layers has been used to form n-p junctions. Measurements showed that the parameter R0A is 1.25×105Ωcm2 for the spectral range 3-5μm. A monolithic linear array of format 1×32, based on a CdHgTe MBE HEL, has been fabricated by growth in the cells of a silicon multiplexer.

A process has been developed for producing linear and two-dimensional array-type photodetector modules (PDMs), including the fabrication of photodetector structures based on heteroepitaxial layers of CdxHg1−xTe and GaAs/AlGaAs grown by molecular-beam epitaxy, fabrication of two-dimensional and linear arrays of silicon multiplexers, and hybrid assembly of PDMs consisting of a photodetector structure and a multiplexer by means of indium microposts. The photoelectric parameters are given for two-dimensional and linear array-type PDMs based on photodiodes for the mid-IR (3-5.5 µm) and far-IR (8-12 µm) regions, operating at temperatures of 78-80 K and 200-220 K. © 2005 Optical Society of America

Narrowing of the linewidth of a diode laser was achieved by an external high-Q microcavity, which was a fused silica sphere 370 μm in diameter. Coupling of the radiation in and out, and matching to a 'whispering gallery' mode of this sphere, were ensured by the method of frustrated total internal reflection. Optical feedback was provided by the Rayleigh scattering. The width of the beat-note spectra of the investigated and reference lasers did not exceed 100 kHz.