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1
Content available remote Nanostructures with Ge–Si quantum dots for infrared photodetectors
Izhnin I. I., Fitsych O. I., Voitsekhovskii A. V., Kokhanenko A. P., Lozovoy K. A., Dirko V. V.
Opto-Electronics Review
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2018
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Vol. 26, No. 3
195--200
EN
In this paper questions of optimization of growth conditions in the method of molecular beam epitaxy for creation of high-efficient quantum dot infrared photodetectors are considered. As a model material system for theoretical investigations, heterostructures with germanium-silicon quantum dots on the silicon surface are chosen. For calculations of the dependencies of quantum dots array parameters on synthesis conditions the kinetic model of growth of differently shaped quantum dots based on the general nucleation theory is proposed. The theory is improved by taking into account the change in free energy of nucleation of an island due to the formation of additional edges of islands and due to the dependence of surface energies of facets of quantum dots on the thickness of a 2D wetting layer during the Stranski–Krastanow growth. Calculations of noise and signal characteristics of infrared photodetectors based on heterostructures with quantum dots of germanium on silicon are done. Dark current in such structures caused by thermal emission and barrier tunneling of carriers, as well as detectivity of the photodetector in the approximation of limitation by generation-recombination noises are estimated. Moreover, the presence of dispersion of quantum dots by size is taken into account in the calculations of the generation-recombination noises. Results of calculations of the properties of structures with quantum dots and their dependencies on growth parameters, as well as the characteristics of quantum dot photodetectors are presented. Comparison of the estimated parameters of quantum dots ensembles and the characteristics of quantum dot photodetectors with experimental data is carried out.
2
Content available remote Ion etching of HgCdTe : properties, patterns and use as a method for defect studies
Izhnin I. I., Mynbaev K. D., Voitsekhovskii A. V., Korotaev A. G., Fitsych O. I., Pociask-Bialy M.
Opto-Electronics Review
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2017
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Vol. 25, No. 2
148--170
EN
Analysis is performed of the contemporary views on the effect of ion etching (ion-beam milling and reactive ion etching) on physical properties of HgCdTe and on the mechanisms of the processes responsible for modification of these properties under the etching. Possibilities are discussed that ion etching opens for defect studies in HgCdTe, including detecting electrically neutral tellurium nanocomplexes, determining background donor concentration in the material of various origins, and understanding the mechanism of arsenic incorporation in molecular-beam epitaxy-grown films.
3
Content available remote Background donor concentration in HgCdTe
Izhnin I. I., Mynbaev K. D., Voitsekhovsky A. V., Korotaev A. G., Fitsych O. I., Pociask-Bialy M., Dvoretsky S. A.
Opto-Electronics Review
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2015
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Vol. 23, No. 3
200-207
EN
Studies of background donor concentration (BDC) in HgCdTe samples grown with different types of technology were performed with the use of ion milling as a means of eliminating the compensating acceptors. In bulk crystals, films grown with liquid phase epitaxy and films fabricated with molecular beam epitaxy (MBE) on Si substrates, BDC of the order of ~10¹⁴ cm⁻³ was revealed. Films grown with metal-organic chemical vapour deposition and with MBE on GaAs substrates showed BDC of the order of ~10¹⁵ cm⁻³. A possibility of assessing the BDC in acceptor (arsenic)-doped HgCdTe was demonstrated. In general, the studies showed the effectiveness of ion milling as a method of reducing electrical compensation in n-type MCT and as an excellent tool for assisting evaluation of BDC.
4
Content available remote Photoluminescence of HgCdTe nanostructures grown by molecular beam epitaxy on GaAs
Izhnin I. I., Izhnin A. I., Mynbaev K. D., Bazhenov N. L., Shilyaev A. V., Mikhailov N. N., Varavin V. S., Dvoretsky S. A., Fitsych O. I., Voitsekhovsky A. V.
Opto-Electronics Review
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2013
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Vol. 21, No. 4
390-394
EN
Photoluminescence (PL) of HgCdTe-based hetero-epitaxial nanostructures with 50 to 1100 nm-wide potential wells was studied. The nanostructures were grown by molecular beam epitaxy on GaAs substrates. A strong degree of alloy disorder was found in the material, which led to the broadening of the PL spectra and a considerable Stokes shift that could be traced up to temperature T~230 K. Annealing of the structures improved the ordering and led to the increase in the PL intensity. A remarkable feature of the PL was an unexpectedly small decrease of its intensity with temperature increasing from 84 to 300 K. This effect can be related to localization of carriers at potential fluctuations and to the specific character of Auger-type processes in HgCdTe-based nanostructures.
5
Content available remote Electrical properties of HgCdTe films grown by MOCVD and doped with as
Izhnin I. I., Savytskyy H. V., Fitsych O. I., Piotrowski J., Mynbaev K. D.
Opto-Electronics Review
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2013
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Vol. 21, No. 2
220-226
EN
Electrical properties of HgCdTe films grown by metal-organic chemical vapour deposition (MOCVD) on GaAs substrates and doped with the As acceptor during the growth were studied. Discrete mobility spectrum analysis was used to extract the parameters of the as-grown films and films after ion milling and during prolonged relaxation of milling-induced defects. The measurements revealed significant compensation of the as-grown MOCVD HgCdTe with As on Te sites being the main defect, residual donor concentration of the order of (2-5)x10¹⁵ cm⁻³ and the presence of some unidentified defects.
6
Content available remote 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.
7
Content available remote Ion milling-assisted study of defect structure of HgCdTe films grown by liquid phase epitaxy
Izhnin I. I., Denisov I. A., Smirnova N. A., Pociask M., Mynbaev K. D.
Opto-Electronics Review
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2010
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Vol. 18, No. 3
328-331
EN
Ion milling, as a tool for ''stirring'' defects in HgCdTe by injecting high concentration of interstitial mercury atoms, was used for studying films grown by liquid phase epitaxy (LPE) on CdZnTe substrates. The films appeared to have very low residual donor concentration (∼10¹⁴ cm⁻³), yet, similar to the material grown by molecular beam epitaxy, contained Te-related neutral defects, which the milling activated electrically. It is shown that ion milling has a stronger effect on HgCdTe defect structure than thermal treatment, and yet eventually brings the material to an ''equilibrium'' state with defect concentration lower than that after low-temperature annealing.
8
Content available remote Conductivity type conversion in p-CdxHg1-xTe
Berchenko N. N., Bogoboyashchyy V. V., Izhnin I. I., Kurbanov K. R., Vlasov A. P., Yudenkov V. A.
Opto-Electronics Review
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2003
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Vol. 11, No. 2
93-98
EN
Investigations and comparative analysis of p-to-n type conductivity conversion processes on the identical samples of vacancy doped p-CdxHg1-xTe (x=0.2) under ion - beam milling (IBM) and anodic oxide annealing and on the identical samples of As-doped p-CdxHg1-xTe (x=0.22) under IBM and anodic oxide annealing have been carried out. The conductivity type conversion has been observed at the considerable depth of the vacancy doped material both under IBM or under anodic oxide annealing while in the case with As-doped material only under IBM. It was considered that conversion in all these processes was determined by the mercury interstitial diffusion from corresponding mercury diffusion source and recombination with its native acceptors-cationic vacancies (in the first case) or with donor complex formations (in the second one). It has been shown that in the vacancy-doped p-CdxHg1-xTe the effective diffusion coefficients for the mercury interstitials that determines the depth of the converted layer are equal each other at equal temperatures either under thermal annealing in the saturated mercury vapaur or anodic oxide annealing. It proves the identity of the mercury concentration in the diffusion source. Absence of the conversion under anodic oxide annealing in the As-doped p-CdxHg1-xTe is explained by insufficient Hg concentration in the source and it matches well with necessary condition for donor complex formation as it takes place under IBM.
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