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Timur V. Malin

Bio: Timur V. Malin is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Molecular beam epitaxy & Doping. The author has an hindex of 8, co-authored 72 publications receiving 302 citations.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the formation of a graphene-like AlN (g-AlN) layer on a (111)-oriented silicon substrate in ammonia molecular beam epitaxy (MBE) has been investigated by the RHEED method.

68 citations

Journal ArticleDOI
TL;DR: In this paper, the temperature and concentration dependences of electron mobility in AlGaN/GaN hetero-structures are studied, and it is established that scattering at charged centers is dominant for samples with low mobility (lower than 1000 cm2/(V s) right up to room temperature.
Abstract: The temperature and concentration dependences of electron mobility in AlGaN/GaN hetero-structures are studied. The mobility for the samples under study at T = 300 K lies in the range of 450–1740 cm2/(V s). It is established that scattering at charged centers is dominant for samples with low mobility (lower than 1000 cm2/(V s) right up to room temperature. These centers are associated with a disordered piezoelectric charge at the heterointerface because of its roughness or with a piezoelectric charge similarly to the Al-GaN barrier because of alloy disorder, as well as with the deformation field around dislocations. Scattering at optical phonons is dominant for samples with mobility exceeding 1000 cm2/(V s) at T = 300 K. Scattering at alloy disorders, heterointerface roughness, and dislocations are dominant at temperatures lower than 200 K. A decrease in the influence of scattering at roughness with improvement of the heterointerface morphology increases room-temperature mobility from 1400 cm2/(V s) to 1700 cm2/(V s).

23 citations

Journal ArticleDOI
TL;DR: In this article, the green band dominates in the photoluminescence spectra of Al x Ga 1− x N:Si films with the Al content higher than 0.5.
Abstract: We report time-resolved and temperature-dependent photoluminescence investigations of green photoluminescence in heavily doped Al x Ga1− x N:Si films grown by molecular beam epitaxy on sapphire substrates. The green band dominates in the photoluminescence spectra of Al x Ga1− x N:Si films with the Al content higher than 0.5. This band is attributed to donor–acceptor and free electron–acceptor transitions involving the same acceptor. Donor and acceptor binding energies of about 50 and 930 meV, respectively, were obtained. The donor was assigned to the Si atom on the Ga/Al site; the acceptor might be the C atom on the N site or a complex comprising a Ga/Al vacancy and a shallow donor.

21 citations

Journal ArticleDOI
TL;DR: The structural, electrical and optical properties of the layers were investigated by atomic force microscopy, X-ray diffraction, Hall, Raman, photoluminescence and cathodoluminecence measurements.
Abstract: The Alx Ga1–xN layers with a wide range of AlN molar fraction (0 < x < 0.6) were grown by ammonia MBE on (0001)-oriented sapphire substrates using silane as the silicon dopant. The structural, electrical and optical properties of the layers were investigated by atomic force microscopy, X-ray diffraction, Hall, Raman, photoluminescence and cathodoluminescence measurements. It was found that doping affects surface morphology, dislocation density and luminescence intensity of the Alx Ga1–xN layers. A sharp decrease of the luminescence intensity for the heavily doped GaN and Al0.3Ga0.7N layers was explained by enhancement of the nonradiative recombination rate in degenerate GaN layers and by an increase in the defect concentration in AlGaN layers. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

20 citations


Cited by
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Journal ArticleDOI
11 Sep 2015-ACS Nano
TL;DR: From statistical analysis, correlations between the piezoelectric coefficients and the electronic and structural properties of the 2D materials that elucidate the origin of the piezolectricity are identified.
Abstract: Two-dimensional (2D) materials present many unique materials concepts, including material properties that sometimes differ dramatically from those of their bulk counterparts. One of these properties, piezoelectricity, is important for micro- and nanoelectromechanical systems applications. Using symmetry analysis, we determine the independent piezoelectric coefficients for four groups of predicted and synthesized 2D materials. We calculate with density-functional perturbation theory the stiffness and piezoelectric tensors of these materials. We determine the in-plane piezoelectric coefficient d11 for 37 materials within the families of 2D metal dichalcogenides, metal oxides, and III–V semiconductor materials. A majority of the structures, including CrSe2, CrTe2, CaO, CdO, ZnO, and InN, have d11 coefficients greater than 5 pm/V, a typical value for bulk piezoelectric materials. Our symmetry analysis shows that buckled 2D materials exhibit an out-of-plane coefficient d31. We find that d31 for 8 III–V semicon...

407 citations

Journal Article
TL;DR: In this paper, high quality AlN epilayers were grown on sapphire substrates by metal organic vapor deposition and exploited as active deep ultraviolet (DUV) optoelectronic materials through the demonstration of AlN metal-semiconductor-metal (MSM) photodetectors.
Abstract: High quality AlN epilayers were grown on sapphire substrates by metal organic vapor deposition and exploited as active deep ultraviolet (DUV) optoelectronic materials through the demonstration of AlN metal-semiconductor-metal (MSM) photodetectors. DUV photodetectors with peak responsivity at 200nm with a very sharp cutoff wavelength at 207nm have been attained. The AlN MSM photodetectors are shown to possess outstanding features that are direct attributes of the fundamental properties of AlN, including extremely low dark current, high breakdown voltage, and high DUV to visible rejection ratio and high responsivity. The results demonstrate the high promise of AlN as an active material for DUV device applications.

152 citations

Journal ArticleDOI
TL;DR: It is found that the presence of a template such as graphene induces enough interlayer charge separation in h-AlN, favoring a graphite-like stacking formation and the interface dipole, calculated per unit cell of the stacks, tends to increase with the number of stacked layers of h- AlN and graphene.
Abstract: Graphite-like hexagonal AlN (h-AlN) multilayers have been experimentally manifested and theoretically modeled. The development of any functional electronics applications of h-AlN would most certainly require its integration with other layered materials, particularly graphene. Here, by employing vdW-corrected density functional theory calculations, we investigate structure, interaction energy, and electronic properties of van der Waals stacking sequences of few-layer h-AlN with graphene. We find that the presence of a template such as graphene induces enough interlayer charge separation in h-AlN, favoring a graphite-like stacking formation. We also find that the interface dipole, calculated per unit cell of the stacks, tends to increase with the number of stacked layers of h-AlN and graphene.

90 citations

Journal ArticleDOI
TL;DR: In this paper, a self-driven, highly sensitive, fast responding GaN nanoflower based UV photodetector is reported, which exhibits very low dark current (approximate to nA) with a very high responsivity (132 mA W-1) and detectivity (2.4 x 10(10) Jones).
Abstract: The rising demand for optoelectronic devices to be operable in adverse environments necessitates the sensing of ultraviolet (UV) radiation. Here, a self-driven, highly sensitive, fast responding GaN nanoflower based UV photodetector is reported. By developing unique structures, the light absorption increases efficiently and a maximum responsivity of 10.5 A W-1 is achieved at 1 V bias. The reported responsivity is the highest among the GaN UV photodetectors on Si substrates and commercially available Si-based UV photodetectors. Under self-driven condition, the photodetector exhibits very low dark current (approximate to nA) with a very high responsivity (132 mA W-1) and detectivity (2.4 x 10(10) Jones). A remarkably high light-to-dark current ratio of approximate to 260 signifies extremely high photodetection gain compared to planar GaN-based photodetectors. The self-driven and biased photodetector device yields highly stable rise and decay time response. A model based on band theory elucidates the origin of self-driven photodetectors. Implementation of the innovative growth design structures assures an exceptionally high sensitivity toward UV signal, which is capable of substituting the existing technology of UV photo-detectors. High responsivity and detectivity from devices based on the GaN nanoflower-like structure with the advantage of high surface/volume ratio can have numerous applications in fabrication of nanoscale optoelectronic high performance devices such as self-driven UV photodetectors.

80 citations

Journal ArticleDOI
TL;DR: In this paper, a review of 2D GaN and AlN structures is presented, starting from three-dimensional (3D) GaN/AlN crystals and multilayer (ML) structures.
Abstract: Potential applications of bulk GaN and AlN crystals have made possible single and multilayer allotropes of these III-V compounds to be a focus of interest recently. As of 2005, the theoretical studies have predicted that GaN and AlN can form two-dimensional (2D) stable, single-layer (SL) structures being wide band gap semiconductors and showing electronic and optical properties different from those of their bulk parents. Research on these 2D structures have gained importance with recent experimental studies achieving the growth of ultrathin 2D GaN and AlN on substrates. It is expected that these two materials will open an active field of research like graphene, silicene, and transition metal dichalcogenides. This topical review aims at the evaluation of previous experimental and theoretical works until 2018 in order to provide input for further research attempts in this field. To this end, starting from three-dimensional (3D) GaN and AlN crystals, we review 2D SL and multilayer (ML) structures, which were...

72 citations