HVPE Method Research Articles

An Experimental Study of Dislocation Dynamics in GaN.

The dynamics of dislocations introduced through indentation or scratching at room temperature into a few GaN layers that were grown using the HVPE, MOCVD and ELOG methods and had different dislocation densities were studied via the electron-beam-induced current and cathodoluminescence methods. The effects of thermal annealing and electron beam irradiation on dislocation generation and multiplication were investigated. It is shown that the Peierls barrier for dislocation glide in GaN is essentially lower than 1 eV; thus, it is mobile even at room temperature. It is shown that the mobility of a dislocation in the state-of-the-art GaN is not entirely determined by its intrinsic properties. Rather, two mechanisms may work simultaneously: overcoming the Peierls barrier and overcoming localized obstacles. The role of threading dislocations as effective obstacles for basal plane dislocation glide is demonstrated. It is shown that under low-energy electron beam irradiation, the activation energy for the dislocation glide decreases to a few tens of meV. Therefore, under e-beam irradiation, the dislocation movement is mainly controlled by overcoming localized obstacles.

Structure and cathodoluminescence properties of Dy3+ and Eu3+ co-doped AlN films

A series of Dy3+ and Eu3+ implanted AlN films grown by HVPE method were prepared. The crystal structure, cathodoluminescence spectra, energy transfer mechanism and chromaticity properties of films were investigated. X-ray diffraction and Raman scattering show the similar trend of stress which increases first and then decreases and saturates at last. According to the cathodoluminescence spectra, there may be an energy transfer process from Dy3+ to Eu3+, which is identified to be the electric quadrupole-quadrupole interaction. Through changing the fluence of Eu3+ respect to Dy3+, the luminescence color of AlN films can be effectively controlled.

Peculiarities of nucleation and growth of InGaN nanowires on SiC/Si substrates by HVPE

The growth of InGaN layers on hybrid SiC/Si substrates with orientations (100), (110), and (111) by the HVPE method was studied at temperatures that wittingly exceed the temperature of InN decomposition onto nitrogen atoms and metallic In (1000oC). On substrates with orientations (110) and (111), the formation of InGaN whisker nanocrystals was observed. The shape and growth mechanisms of nanocrystals were investigated. It is shown that nanocrystals nucleate on the (111) surface only inside V-defects formed at the points where screw dislocations exit onto the surface. On the (110) surface, nanocrystals are formed only on pedestals that arise during the film growth. An explanation is given for the difference in the growth mechanisms of nanocrystals on substrates of different orientations. Keywords: InGaN, heterostructures, SiC on Si, silicon, whisker nanocrystals, nanostructures, atomic substitution method

Особенности зарождения и роста нитевидных нанокристаллов InGaN на подложках SiC/Si методом хлорид-гидридной эпитаксии

The growth of InGaN layers on hybrid SiC/Si substrates with orientations (100), (110), and (111) by the HVPE method was studied at temperatures that wittingly exceed the temperature of InN decomposition onto nitrogen atoms and metallic In (1000C). On substrates with orientations (110) and (111), the formation of InGaN nanocrystals was observed. The shape and growth mechanisms of nanocrystals were investigated. It is shown that nanocrystals nucleate on the (111) surface only inside V-defects formed at the points where screw dislocations exit onto the surface. On the (110) surface, nanocrystals are formed only on pedestals that arise during the film growth. An explanation is given for the difference in the growth mechanisms of nanocrystals on substrates of different orientations.

Light Emitting Properties of Si Micro Single Crystal Grown by Mixed-Source HVPE Method

Light Emitting Properties of Si Micro Single Crystal Grown by Mixed-Source HVPE Method

Самоорганизация состава пленок Al-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-N, выращенных на гибридных подложках SiC/Si

Using spectral ellipsometry, Raman spectroscopy, and scanning microscopy with an X-ray spectrometer (EDS), the phenomenon of self-organized change in the composition of AlxGa1-xN epitaxial layers during their growth by chloride-hydride epitaxy (EDX) on SiC / Si (111) hybrid substrates was revealed. It was found that during the growth of AlxGa1-xN layers with a low, about 11-24% Al content, interlayers (domains) appear, consisting of AlGaN stoichiometric composition. A qualitative model has been proposed, according to which self-organization in composition arises due to the effect of two processes on the growth kinetics of the AlxGa1-xN film. The first process is associated with the competition of two chemical reactions proceeding at different rates. One of these reactions is the AlN formation reaction; the second is the reaction of GaN formation. The second process, closely related to the first, is the appearance of elastic compressive and tensile stresses during the growth of AlxGa1-xN films by the CGE method on SiC / Si (111). Both processes influence each other, which leads to a complex pattern of aperiodic changes in the composition over the thickness of the film layer. Keywords: A3B5 compounds, wide-gap semiconductors, AlGaN, AlN, GaN, silicon carbide on silicon, self-organization of the composition, HVPE method, solid solutions, heterostructures.

Fe-doped GaN grown on stirring-assisted Na-flux process GaN thick film and its application on Ohmic contact UV detector

Abstract Na-flux method is the most promising approach to grow GaN thick film substrate for GaN homoepitaxy. Here, the influence of solution stirring on grown GaN crystal morphology, crystal quality, dislocation density and impurity concentration was assessed for GaN crystal growth by Na-flux method. It is proved that the crystallinity, surface roughness and dominated orientation of the GaN thick layers are greatly influenced by stirring process, revealing a direct and correlated growth mechanism for the growth of GaN using Na-flux method. Notably, the surface roughness was reduced by three orders of magnitude under stirring (compared to un-stirred sample). This stirring-assisted GaN thick film was then used as seed layer to grow high resistance Fe-doped GaN epitaxial layer by applying HVPE method. On which Ohmic contact was successfully fabricated and an UV-detector with a high detectivity of ~1013 Jones, which was among the highest values, and fast response (rise time of 100 ms, decay time of 160 ms) was obtained.

Growth Mechanism and Characterization of AlN Microspheres by HVPE Method

Growth Mechanism and Characterization of AlN Microspheres by HVPE Method

GaN Single Crystalline Substrates by Ammonothermal and HVPE Methods for Electronic Devices

Recent results of GaN bulk growth performed in Poland are presented. Two technologies are described in detail: halide vapor phase epitaxy and basic ammonothermal. The processes and their results (crystals and substrates) are demonstrated. Some information about wafering procedures, thus, the way from as-grown crystal to an epi-ready wafer, are shown. Results of other groups in the world are briefly presented as the background for our work.

GaN-based LEDs using Homo-Epitaxial technology and the Progress and Challenges of HVPE method

GaN and other group III-nitrides are promising materials for optoelectronic devices applications. Currently, sapphire is the most widely used substrate material for GaN LEDs due largely to economic considerations. During the past decade or so, free-standing GaN substrates fabricated via HVPE have gained technological importance and circumventing the shortcomings of sapphire substrates in terms of thermoconductivity and lattice mismatch. This technology, however, does have its own set of challenges. This review summarizes the current state of freestanding GaN substrate technology, the challenges it is facing, and outlook.

Erratum: The Mechanism of Growth of GaN Films by the HVPE Method on SiC Synthesized by the Substitution of Atoms on Porous Si Substrates [ECS J. Solid State Sci. Technol., 7, P480 (2018)

Erratum: The Mechanism of Growth of GaN Films by the HVPE Method on SiC Synthesized by the Substitution of Atoms on Porous Si Substrates [ECS J. Solid State Sci. Technol., 7, P480 (2018)

Application of XRD methods for the pilot studies of new functional materials for photonics

We report on the detailed study of the structural properties of the large-area GaN slabs grown by HVPE method over ceramic support with the use of X-ray analysis with powder diffraction technique. The impact of V/III ratio on the specifics of the crystal structure of the material was studied. It was shown, that depending of growth condition either texture along (00.2) axis, i.e., along c axis in polar GaN, or along (11.0) axis, i.e., normal to so-called m-plane GaN are formed.

The Mechanism of Growth of GaN Films by the HVPE Method on SiC Synthesized by the Substitution of Atoms on Porous Si Substrates

The mechanisms of nucleation and growth of GaN films on porous silicon substrates with a buffer layer of silicon carbide grown by new method of substitution of atoms directly in the subsurface layer of the Si substrate were studied. P-type Si(111) plates with a deposited system of periodic mesopores of a diameter of 17 nm and a depth of 1.5 μm were used as the substrates for growth of SiC buffer layer. The buffer AlN layers of a thickness of the order of 500 nm followed by GaN layers of a thickness of the order of 5 μm were deposited by the HVPE method on SiC/Si substrates prepared in different ways. SEM micrographs, Raman and photoluminescence spectra of these samples are given. The influence of the Si substrate preparation method and the conditions of the SiC layer synthesis on the growth mechanisms of both AlN and GaN films has been experimentally revealed. The formation of two types of V-defects during the growth of GaN was observed. A theoretical model for the formation of defects of the first and second types is developed.

Crystalline Properties of GaN Layers Grown on PSS and AlN Buffered PSS by HVPE Method

Crystalline Properties of GaN Layers Grown on PSS and AlN Buffered PSS by HVPE Method

Large-roll growth of 25-inch hexagonal BN monolayer film for self-release buffer layer of free-standing GaN wafer.

Hexagonal boron nitride (h-BN) is known as promising 2D material with a wide band-gap (~6 eV). However, the growth size of h-BN film is strongly limited by the size of reaction chamber. Here, we demonstrate the large-roll synthesis of monolayer and controllable sub-monolayer h-BN film on wound Cu foil by low pressure chemical vapor deposition (LPCVD) method. By winding the Cu foil substrate into mainspring shape supported by a multi-prong quartz fork, the reactor size limit could be overcome by extending the substrate area to a continuous 2D curl of plane inward. An extremely large-size monolayer h-BN film has been achieved over 25 inches in a 1.2” tube. The optical band gap of h-BN monolayer was determined to be 6.0 eV. The h-BN film was uniformly transferred onto 2” GaN or 4” Si wafer surfaces as a release buffer layer. By HVPE method, overgrowth of thick GaN wafer over 200 μm has been achieved free of residual strain, which could provide high quality homo-epitaxial substrate.

The efficiency of UV LEDs based on GaN/AlGaN heterostructures

The UV LED GaN/AlGaN heterostructures obtained by HVPE approach were investigated. It was shown that the peak wavelength of UV LEDs was in the range of 360-380 nm with FWHM of 10-13 nm. At operating current of 20 mA, the active region temperature Tj was 43°C, the output optical power and efficiency - 1.14 mW and 1.46%, respectively. It was shown that the use of HVPE method allowed to achieve a high degree of structural perfection of epitaxial structures.

Ammonothermal growth of GaN crystals on HVPE-GaN seeds prepared with the use of ammonothermal substrates

Results of gallium nitride crystallization by ammonothermal method are presented. GaN crystals grown earlier by a HVPE method on an ammonothermal GaN substrate and an MOCVD-GaN/sapphire template were used as seeds. Structural and optical properties of the obtained materials are studied and compared. Large radius of curvature (>100m) and low dislocation density (7×104cm−2) can be reproduced in the ammonothermal method using an HVPE-GaN seed grown before on ammonothermal GaN. This proves that the use of HVPE-GaN grown on ammonothermal seeds allows to reproduce high crystallinity in a subsequent ammonothermal growth. It also demonstrates that a much more effective multiplication process of high quality GaN can be launched using a combination of the ammonothermal and HVPE methods.

The control of mechanical bow for GaN substrate grown by HVPE with relatively longer radius of lattice curvature

AbstractWe are going to develop GaN growth process by HVPE method, which shows the near null value of free standing (FS)‐GaN wafer bowing after laser lift‐off (LLO) process in order to reduce the production cost of GaN substrate. The 309 to 318 µm thick HVPE grown GaN layers on sapphire shows 574 to 669 µm of as grown bows, and –299 to 95 µm of bow after LLO process. The 440 µm thick HVPE grown GaN layer on sapphire shows 693 µm of as grown bow, and –4 µm of bow after LLO process. From this GaN template, we could get the 356 µm thick FS‐GaN wafer with 2 µm of bow after polishing. This GaN substrate shows at least 43.87 m of the radius of lattice curvature evaluated by 9‐points measuring of (004) rocking curve along center line parallel to the main flat plane. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Epitaxial silicon carbide on a 6″ silicon wafer

The results of the growth of silicon-carbide films on silicon wafers with a large diameter of 150 mm (6″) by using a new method of solid-phase epitaxy are presented. A SiC film growing on Si wafers was studied by means of spectral ellipsometry, SEM, X-ray diffraction, and Raman scattering. As follows from the studies, SiC layers are epitaxial over the entire surface of a 150-mm wafer. The wafers have no mechanical stresses, are smooth, and do not have bends. The half-width of the X-ray rocking curve (FWHMω−θ) of the wafers varies in the range from 0.7° to 0.8° across the thickness layer of 80–100 nm. The wafers are suitable as templates for the growth of SiC, AlN, GaN, ZnO, and other wide-gap semiconductors on its surface using standard CVD, HVPE, and MBE methods.

A novel porous substrate for the growth of high quality GaN crystals by HVPE

This manuscript describes a high temperature annealing process to prepare a porous substrate. The substrate was used for the growth of GaN by using HVPE method to provide reduced residual stress and low defect density.