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Registration Number

0216U005850, 0111U002161 , R & D reports

Title

Influence of radiation defects on physical properties of elementary semiconductors and composite nanostructures (Si-Ge, AlGaN/GaN, carbonic nanjtubes).

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Head

Danilchenko B.A.,

Registration Date

29-02-2016

Organization

Institute of physics NASU

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The object of the research is germanium, heavily boron-doped silicon, gallium nitride, carbon nanotubes. The aim of the research is the establishment the role of intrinsic interstitials and vacancies in the formation of defects in germanium; the development of the method for controllable change electrical and optical properties of germanium; the study the charge transport phenomena in nitride heterostructures in strong electric fields; the investigation the radiation influence the electrical and sorption properties of single carbon nanotubes and their bundles. Methods: Fourier transform infrared spectroscopy, Hall effect, current - voltage characteristics and conductivity in pulsed mode, noise spectroscopy. It was established that doping of Ge with tin drastically changes the reactions involving intrinsic vacancies and interstitials. Upon the irradiation vacancies V effectively interact with tin atoms and form with them SnV and SnV2 centers. This leads to a significant reduction in the introduction efficiency of the main recombination centers: divacancies and vacancy+oxygen. Important, that vacancy+oxygen centers occur only at temperatures higher than 310 K what indicates that vacancies are immobile up to this temperature. Besides, the vacancy+oxygen complexes exist in much narrow temperature range (310 380 K) than in undoped Ge (80 420 K). The vacancies immobility up to high temperatures enables us to confirm experimentally that intrinsic interstitial atoms I in Ge become mobile at temperatures T> 180 K. It is shown that during diffusion I atoms efficiently interact with oxygen with formation of IO centers. It was found that annealing of IO occurs by both dissociation and diffusion. The IO dissociation is accompanied by recapture of the released I atoms by another IO centers with formation of I2O complexes. Diffusing IO interact with vacancy+oxygen centers what leads to an increase of the dimers O2 concentration. The absorption lines corresponding to defects involving intrinsic interstitial and oxygen atoms are identified. The dependence of the electron velocity in GaN heterostructures on the electric field intensity up to 0.3 MV/cm are investigated. The revealed value for velocity is 6.8?107 cm/sec what corresponds to the quasi ballistic electron motion and exceeds the ones which today are known for semiconductors. Such high velocity gives an opportunity to increase the performance of modern GaN - based devices. It was experimentally found that electron transport in carbon nanotubes follows Tomonaga Luttinger liquid model regardless on the type of radiation (gamma quanta, high-energy electrons) and environment (vacuum, hydrogen). With the use of noise spectroscopy we have found that conductivity mechanism in carbon nanotubes changes with the temperature from hopping (4.2 20 K) up to quantum through Tomonaga Luttinger liquid mechanism (20 200 K) and then, at higher temperatures, to the diffusion mechanism (200 300 K). The theory of radiation defects formation in carbon nanotubes when irradiated in a various gaseous environment was developed. According to this theory the high-energy particles initially transfer the energy to the gas atom which subsequently interacts with the surface of the nanotubes to form defects. The such mechanism could be implemented during irradiation of graphene and nanolayers also. It was experimentally and theoretically shown that the effectiveness of defects creation no monotonously depends on the mass of the atoms of gas environment. The desorption kinetics of helium isotopes (3He and 4He), molecules of hydrogen H2 and deuterium D2 from carbon nanotube bundles was investigated. The dependence of the temperature for transition from the classical to the quantum diffusion on the atomic mass of gas is determined. Experimentally shown, that this temperature follows linear dependence against the inverse mass of gas molecule and this is consistent with the theoretical prediction. All the above results were not known in the literature up to date. The obtained results can be used in the development of technology production of the devices for solid state electronics with preset parameters and increased resistance to the effects of ionizing radiation. The implementation of the high electron velocity in GaN heterostructures devices will be the essential progress in high speed (terahertz frequency range) electronics. Results obtained in the study of electrical properties of carbon nanotubes irradiated in various gas environments are important in view of the practical application of radiation technologies for modifying the properties of carbon nanotubes, which are widely used to create a new solid-state devices of nanoelectronics and in hydrogen energy technologies.

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Войцехівська Олена Олександрівна
Данильченко Борис Олександрович
Дуванський Андрій Володимирович
Крайчинський Анатолій Миколайович
Лев Сергій Богданович
Самочерних Сергій Володимирович
Соснін Михайло Георгійович
Трипачко Микола Олександрович
Хіруненко Людмила Іванівна
Ясковець Іван Іванович

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2020-04-02