The results of studying the conditions for obtaining an atomically smooth surface of GaSb substrates are presented for the first time. It has been shown experimentally that it is possible to improve the surface quality of the samples by changing the annealing conditions. The smallest roughness of 1.3 nm was obtained for an annealing time of 16 min at a temperature of 650°C in a flow of trimethylantimony and H 2 .

For the first time, the results of a study of the conditions for obtaining an atomically smooth surface of GaSb substrates are presented. It is shown experimentally that it is possible to improve the surface quality of the samples by changing the annealing conditions. The lowest obtained roughness of 1.27 nm was obtained at an annealing time of 16 minutes at a temperature of 650°C in the flow of TMSb and H2.

The capabilities of metalorganic vapor-phase epitaxy (MOVPE) in fabrication of structures with thin (1–2 nm) alternating InAs/GaSb layers on a GaSb substrate are studied. The characteristics of these structures were examined using transmission electron microscopy and methods of photo- and electroluminescence. It was found that two GaInAsSb solid solutions of different compositions were formed in the active regions of structures in the given growth conditions. The fabricated system was characterized by an emission wavelength of 4.96 μm at a temperature of 77 K. The results reveal new opportunities for bandgap engineering of semiconductor structures based on InAs/GaSb, which are designed for optoelectronic devices operating in the infrared range, provided by MOVPE.

This work demonstrates the possibility of growing Type-II InAs/GaSb superlattices by MOCVD. The Type-II InAs/GaSb superlattices consisting of 20 pairs of alternating InAs and GaSb layers of equal thickness (1 nm / 2 nm) were grown at a temperature of 500°C. The obtained structures were studied by transmission electron microscopy and electroluminescence. The electroluminescence spectra demonstrated a maximum at about 0.25 eV.

Capabilities of Metal Organic Chemical Vapor Deposition (MOCVD) method for fabrication of multi-layer InAs/GaSb structures with thin (1-2 nm) layers on GaSb substrates were studied. Properties of fabricated structures were studied by transmission electron microscopy and photo- and electro-luminescence. It was found that during growth, two solid solutions GaInAsSb of different compositions were formed in the active region of the structures. The system obtained is characterized by emission at the wavelength of 4.96 µm at the temperature 77 K. Our results demonstrate new capabilities of MOCVD method for bandgap engineering of semiconductor structures based on InAs/GaSb and designed for optoelectronic devices for infrared wavelength range.

In this article, we investigated the effect of technological growth parameters by metal-organic chemical vapor deposition (MOCVD) method on the thickness of the transition layers, which affect the value of tensile strain in the structure, in the InAs/GaSb superlattice. We consider that the thickness of transition layers depends on the roughness of the growth surface and the technological conditions of growing single layers in the superlattice. At the first stage, we have determined the optimal annealing parameters for the minimization of the substrate roughness as T = 650 °C and t = 8 min, with a minimum value of 1.1 nm. At the second stage, studies were carried out on the effect of the sequence of elements and the delay time of reagent supply during the growth of InAs and GaSb layers on the quality of heterointerface. The stress analysis of the obtained structures was performed by reflectance anisotropy spectroscopy. It was shown that a superlattice becomes less tense with the increase in the number of pairs of alternating layers.

This study is dedicated to the development of the technology of InAs/GaSb superlattice by MOCVD. There was obtained an InAs/GaSb superlattice consisting of 10 pairs of alternating layers of InAs and GaSb grown at the temperature of 500 degrees C. The obtained structures were studied by transmission electron microscopy (TEM) and photoluminescence (PL). Also, a light-emitting structure with quantum well was obtained to substantiate the developed technology.

This work presents the results of technology development of the growing heterostructures with strained InAs/GaSb superlattice for diode by MOCVD. The InAs/GaSb superlattices consisting of 20 pairs of alternating layers of InAs and GaSb were grown at the temperature of 500 degrees C with similar thickness of the layers. Layer thicknesses were 1 nm, 2 nm and less than 1 nm. Diodes based on these structures were produced by photolithography and etching of meza diodes. The obtained structures were studied by scanning electron microscopy and electroluminescence.

This study is dedicated to developing the technology for growing InAs/GaSb superlattices (SLs) by MOCVD. The structures were studied by transmission electron microscopy (TEM) and photoluminescence (PL) methods. We concluded that hetero-interface sharpness is not affected by the pause time between growth stages for separate layers or by switching the layer direction. A possible interpretation for the spectra of SLs was suggested.

This article presents a review of the literature data and our own data concerning the effects of terahertz radiation on the state of DNA, the chromosome, and the activity of genes in the cells of micro-organisms and eukaryotes. The phenotypical changes that accompany the irradiation of intact organisms are described. Mutagenic effects and epigenetic pathways of action are considered. Possible mechanisms of the nonthermal action of terahertz radiation are discussed. (C) 2017 Optical Society of America

Terahertz radiation (0.1–10 THz) is increasingly becoming a factor of human habitat. The studyof the consequences of radiation allows one to estimate its possible biological danger. Our data indicate thatthe terahertz irradiation of parental Drosophila shortens the period of embryonic development of their firstgeneration descendants. Significant deviations of data from the control were found, when both females andmales were experimental parents. The highest portion of animals with accelerated hatching as compared withthe control was found in progenies from irradiated females. The shift of maximal hatching peak to an earlierperiod was found in descendants of both sexes. Thus, it was for the first time found on the model object (Drosophila)that the terahertz irradiation of parents can have positive or negative consequences in the first generationdescendants.

This review considers experimental research of the biological effects of terahertz radiation and their results, which provide a basis for medical application of laser terahertz radiation. Therapeutic and diagnostic uses of laser terahertz radiation are described with reference to preliminary basic investigations at the organismic, cell, and molecular levels. It is emphasized that preliminary basic studies of this kind are of importance as another avenue of research to design diagnostic and therapeutic techniques in addition to terahertz imaging and spectroscopy.

The effects of terahertz radiation (0.1–2.2 THz) on the dynamics of reaching the imago stage by drosophila of the F1 progeny obtained from the crossing of irradiated and unirradiated parental individuals in different combinations were studied. A shift in the maximum emergence peak for an earlier period and a shortening of the period of reaching the adult state were found in the progeny of both sexes obtained from irradiated females. The development up to the imago stage significantly differs in the progeny of irradiated males and irradiated females in a number of parameters. It was suggested that the effect of terahertz radiation on the dynamics of the onset of the imago stage can be associated with one or different mechanisms that change the expression of the genes and signaling pathways that control the development of drosophila.

Virgin drosophila females were stressed by placing them in a limited space without food for 3 h. Some of the flies were exposed to terahertz radiation for 30 min in the 0.1–2.2 THz frequency range. Irradiated and unirradiated flies were then mated with males. The F1 progeny of egg cells that were mature or immature at the time of radiation (laying at the first–second and ninth–tenth days after the radiation) were studied. The lifespan of separate individuals were registered. It was demonstrated that terahertz radiation has no effect on the average and absolute lifespan of F1 progeny of both sexes. Sexual dimorphism was found in the survival response to terahertz radiation. The survival curves of males that were developed from egg cells that were immature or mature at the time of radiation significantly differ from the appropriate control, while the survival curves for females are similar to the control. It was concluded that terahertz radiation has a longterm influence on the survival of F1 male progeny.

An investigation into the effect of nonionizing terahertz radiation (0.1–10 THz) on living organisms is urgent due to the recent development of modern technologies employing such radiation. The aim of this study was to establish the impact of terahertz radiation on successive generations of fruit flies. The effects of terahertz radiation on the survival ability and lifespan of the Oregon-R strain of Drosophila melanogaster proved to be diverse: they were negative or neutral at early life stages and positive at late stages. The female flies exposed to the radiation showed increased survival rate during the second half of the life of imago. The males demonstrated low sensitivity to the radiation. There were no significant differences noted in the dynamics of maturation and total number of offspring between the female flies that were exposed to the radiation and those that were not. The results of the study practically did not depend on the sex and maturity stage of the oocytes irradiated.

Virgin female fruit flies were stressed by placement into a confined space without food for 3 hours. Some flies were subjected to terahertz irradiation (0,1-2,2 THz) for the last 30 min. Irradiated and nonirradiated females were then copulated with males. We investigated the F1 progeny of fruit flies with mature and immature oocytes at the moment of irradiation (days of oviposition: 1-2 and 9-10 after irradiation). Life span of individual flies was evaluated. It was demonstrated that terahertz radiation does not influence the absolute and average lifespan of the F1 progeny in both sexes. In response to terahertz irradiation the sexual dimorphism was detected. Survival curves of males, developed from mature and immature oocytes at the time of irradiation, differ significantly from the appropriate control, whereas in the case of females the survival curves are similar to the control. It is concluded that terahertz radiation has a remote effect on a survival of the F1 male progeny.

Virgin fruit fly females and males were stressed by placement into a confined space without food for 3 h. Part of stressed flies were subjected to terahertz irradiation (0.1–2.2 THz) during 30 min. Life span of individual flies was evaluated. Terahertz radiation had some positive influence on male survival during the stage of monotonic decrease in flies number and negative effect during the stage of relatively stable number of flies. The survival of irradiated females on the stage of sharp decline in the number of flies was higher than in stressed and control females. Authors propose that terahertz radiation has an indirect effect on gene expression and signaling pathways which control the survival and life span of Drosophila.

Life span control is realized by the interaction of many genetic factors with the environment. Due to the development of modern technologies based on nonionized terahertz radiation (0.1–10 THz), the investigation of the influence of this radiation on living organisms is urgent. In our study, the effects of terahertz radiation on the survival and lifespan of the Oregon R line of Drosophila melanogaster were multidirectional, depending on the age of the insects. The terahertz effect on survival was negative or neutral in early life and positive in later life. In the drosophila response to terahertz radiation, sex differences were manifested. Males were not very sensitive to terahertz radiation. The survival of irradiated females increased significantly in the second half of the imago life. Irradiation of the drosophila did not significantly affect mean and maximal values of lifespan, but the gap between the values of the mean lifespans of males and females in this group of insects was increased. The mechanisms for the effects of terahertz radiation on survival and lifespan might be associated with changes in the cellular membrane, gene expression, and signaling pathways controlling these features.

Virgin fruit fly females were stressed by placement into a confined space without food for 2.5 hours. Some flies were subjected to terahertz radiation (0.1–2.2 THz) for the last 30 min. Then females were copulated with males. Offspring F1 from oocytes which were mature or immature at exposure (oviposition in 1–2 or 9–10 days after irradiation) was studied. Stress induces a rejection of the offspring maturation dynamics to imago from external control (offspring of flies which was maintained in standard conditions). In offsping from mature oocytes of irradiated flies the dynamics of male maturation to imago was different from internal control (offspring of stressed unirradiated flies). The number of imago males decreased. The dynamics of female maturation to imago coincides with laboratory control. In offsping from immature oocytes of irradiated flies the dynamics of female and male maturation and the number of flies were not significantly different from the internal control. It was concluded that only mature oocytes are sensitive to THz radiation influence.