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MBE-grown MCT hetero- and nanostructures for IR and THz detectors

Dvoretsky S. A., Mikhailov N. N., Remesnik V. G., Sidorov Y. G., Shvets V. A., Ikusov D. G., Varavin V. S., Yakushev M. V., Gumenjuk-Sichevska J. V., Golenkov A. G., Lysiuk I. O., Tsybrii Z. F., Shevchik-Shekera A. V., Sizov F. F., Latyshev A. V., Aseev A. L.

Opto-Electronics Review

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2019

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Vol. 27, No. 3

282--290

EN

We present an overview of our technological achievements in the implementation of detector structures based on mercury cadmium telluride (MCT) heterostructures and nanostructures for IR and THz spectral ranges. We use a special MBE design set for the epitaxial layer growth on (013) GaAs substrates with ZnTe and CdTe buffer layers up to 3” in diameter with the precise ellipsometric monitoring in situ. The growth of MCT alloy heterostructures with the optimal composition distribution throughout the thickness allows the realization of different types of many-layered heterostructures and quantum wells to prepare the material for fabricating single- or dual-band IR and THz detectors. We also present the two-color broad-band bolometric detectors based on the epitaxial MCT layers that are sensitive in 150–300-GHz subterahertz and infrared ranges from 3 to 10μm, which operate at the ambient or liquid nitrogen temperatures as photoconductors, as well as the detectors based on planar HgTe quantum wells. The design and dimensions of THz detector antennas are optimized for reasonable detector sensitivity values. A special diffraction limited optical system for the detector testing was designed and manufactured. We represent here the THz images of objects hidden behind a plasterboard or foam plastic packaging, obtained at the radiation frequencies of 70, 140, and 275 GHz, respectively.

2

Defects in HgCdTe grown by molecular beam epitaxy on GaAs substrates

Izhnin I. I., Izhnin A. I., Savytskyy H. V., Fitsych O. I., Mikhailov N. N., Varavin V. S., Dvoretsky S. A., Sidorov Y. G., Mynbaev K. D.

Opto-Electronics Review

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2012

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Vol. 20, No. 4

375-378

EN

The Hall effect and photoluminescence measurements combined with annealing and/or ion milling were used to study the electrical and optical properties of HgCdTe films grown by molecular-beam epitaxy on GaAs substrates with ZnTe and CdTe buffer layers. Unintentional donor doping, likely from the substrate, which resulted in residual donor concentration of the order of 10¹⁵ cm⁻³, was observed in the films. Also, acceptor states, possibly related to structural defects, were observed.

3

Influence of near-surface graded-gap layers on electrical characteristics of MIS-structures based on MBE grown HgCdTe

Voitsekhovskii A. V., Nesmelov S. N., Dzyadukh S. M., Varavin V. S., Dvoretskii S. A., Mikhailov N. N., Sidorov Y. G., Yakushev M. V.

Opto-Electronics Review

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2010

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Vol. 18, No. 3

259-262

EN

The paper examines influence of near-surface graded-gap layers on electrical characteristics of MIS-structures fabricated on heteroepitaxial Hg₁₋xCdxTe films grown by molecular beam epitaxy (MBE). Two types of insulators, i.e., two-layer SiO₂Si₃N₄ and anodic oxide films were used. As it is seen from the depth and width of the valley on the C-V characteristics, the capacitance is found to vary in a wide range, in contrast to the structures without graded-gap layers. It is shown that the graded-gap layer under MIS-structures with x = 0.22 effectively reduces the tunnelling generation via deep levels and increases a lifetime of minority carriers in the space charge region and its differential resistance. The properties of the HgCdTe-insulator interfaces are studied.

4

Capacitance-voltage characteristics of MIS-structures on the basis of graded-band MBE Hg₁₋xCdxTe at passivation by epitaxially grown in situ CdTe

Voitsekhovskii A. V., Nesmelov S. N., Dzyadukh S. M., Varavin V. S., Dvoretskii S. A., Mikhailov N. N., Sidorov Y. G., Yakushev M. V.

Opto-Electronics Review

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2010

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Vol. 18, No. 3

263-266

EN

The electrical properties of the interface between Hg₁₋xCdxTe (x = 0.22 and x = 0.32-0.36) and CdTe prepared in situ molecular beam epitaxy were estimated at 77 K. The methods of determination of main parameters of interface semiconductor/insulator and insulator from capacitance-voltage characteristics of MIS-structures based on graded-band Hg₁₋xCxTe have been developed. The fixed charge states density, fast surface states density, and density of mobile charge are obtained from capacitance-voltage measurements. For improvement in stable and electrical strength of insulator coating for several samples over CdTe additional protective layers SiO₂-Si₃N₄ are formed for x = 0.22 and ZnTe for x = 0.32-0.36.

5

320x256 HgCdTe IR FPA with a built-in shortwave cut-off filter

Vasilyev V. V., Varavin V. S., Dvoretsky S. A., Marchishin I. V., Mikhailov N. N., Predein A. V., Remesnik V. G., Sabinina I. V., Sidorov Y. G., Susliakov O. A.

Opto-Electronics Review

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2010

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Vol. 18, No. 3

236-240

EN

A photovoltaic detector design based on the graded band gap HgCdTe MBE structure with high conductivity layer (HCL) at interface, which provides photodiodes series resistance and a shortwave cut.off filter is developed. The optimal HCL parameters giving high quantum efficiency and minimal noise equivalent temperature difference were determined by calculations and experimentally confirmed. The hybrid 320x256 IR FPA operating in 8-12 μm spectral range was fabricated. The threshold power responsivity and minimal noise equivalent temperature difference values at wavelength maximum were 1.02x10⁻⁷ W/cm², 4.1x10⁸ V/W and 27 mK, respectively.

6

HgCdTe epilayers on GaAs : growth and devices

Varavin V. S., Vasiliev V. V., Dvoretsky S. A., Mikhailov N. N., Ovsyuk V. N., Sidorov Y. G., Suslyakov A. O., Yakushev M. V., Aseev A. L.

Opto-Electronics Review

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2003

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Vol. 11, No. 2

99-111

EN

View of basic and specific physical and chemical features of growth and defect formation in mercury cadmium telluride (MTC) heterostructures (HS's) on GaAs substrates by molecular beam epitaxy (MBE) was made. On the basis of this knowledge a new generation of ultra high vacuum set, ultra-fast ellipsometer of high accuracy and automatic system for control of technological processes was produced for reproducibility of growth MCT HS's on substrates up to 4'' in diameter. The development of industrially oriented technology of MCT HS's growth by MBE on GaAs substrates 2'' in diameter and without intentional doping is presented. The electrical characteristics of n-type and p-type of MCT HS's and uniformity of MCT composition over the surface area are excellent. The residual donor and acceptor centres are supposed as hypothetically tellurium atoms in metalic sublattice ("antisite" tellurium) and double-ionised mercury vacancies. The technology of fabricating focal plane arrays is developed. The high quality characteristics of infrared detectors conductance and diode mode are measured. Calculations of detector parameters predicted the improvement in serial resistance and detectivity of infrared diode detectors based on MCT heterostructures with graded composition throughout the thickness.

7

Conductivity anisotropy of CdHgTe MBE layers with a periodic surface microrelief

Voitsekhovskii A. V., Kokhanenko A. P., Nesterovich N. V., Varavin V. S., Dvoretsky S. A., Sidorov Y. G., Mikhalov N. N.

Opto-Electronics Review

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2003

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Vol. 11, No. 2

151-154

EN

The surface microrelief of CdHgTe layers grown by molecular beam epitaxy (MBE) method has been studied by means of atomicforce microscopy. A periodic surface microrelief in the form of an ordered system of extended waves with the characteristic period 0.1-0.2 um has been detected on epilayers grown at increased temperatures. Angular dependencies of the conductivity at 77 K have been measured and the conductivity anisotropy has been detected with a minimum in the direction transverse to microrelief waves. A feature of the transmission spectrum and the spectrum change after film annealing are observed. It is assumed that walls growing in the direction from the substrate to the surface are formed under microrelief wave slopes. Such structure can cause the observed feature of the transmission spectrum if the adjacent walls have different composition. In this work a calculation of spectral characteristics taking into account the influence of variable gap composition and nonuniformity of the composition through the depth has been carried out.

8

HgCdTe MBE grown LWIR linear arrays

Sizov F. F., Vasiliev V. V., Esaev D. G., Ovsyuk V. N., Sidorov Y. G., Reva V. P., Golenkov A. G., Zabudsky V. V., Gumenjuk-Sychevskaya J. V.

Opto-Electronics Review

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2001

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Vol. 9, No. 4

391-396

EN

Mercury-cadmium-telluride (MCT) 2x64 linear arrays with silicon readouts were designed, manufactured and tested. MCT layers were grown by MBE method on (103) GaAs substrates with CdZnTe buffer layers. 50x50 [mi]m n-p-type photodiodes were formed by boron implantation. The parameters of long wavelenght infrared MCT linear arrays with cutoff wavelenght ʎco ≈ 10.0-12.2 [mi]m and Si readouts were tested separately before hybridisation. The HgCdTe arrays and Si readouts were hybridised by cold welding In bumps technology. Dark carrier transport mechanisms in these diodes were calculated and compared with experimental data. Two major curment mechanisms were included into the current balance equations: trap-assisted tunnelling and Shockley-Reed-Hall generation-recombination processes via a defect trap level in the gap. Other current mechanisms (band-to-band tunnelling, bulk diffusion) were taken into account as additive contributions. Tunnelling rate characteristics were calculated within k-p-aproximation with the constant barrier electric field. Good agreement with experimental data was obtained.