Migration-Enhanced Epitaxy of GaAs and AlGaAs

Horíkoshi, Yoshiji; Kawashima, Minoru; Yamaguchi, Hiroshi

doi:10.1143/jjap.27.169

Cited by 364 publications

(88 citation statements)

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“…The 4 nm AlN barriers were grown using migration enhanced epitaxy (MEE) [23] to ensure a smooth heterointerface between AlN and GaN by avoiding excess Al.…”

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confidence: 99%

Deep-UV emission at 219 nm from ultrathin MBE GaN/AlN quantum heterostructures

Islam

Protasenko

Lee

et al. 2017

Applied Physics Letters

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The ruggedness, portability, high-efficiency, and microfabrication benefits of solid-state semiconductor light sources over conventional lamps became clear in the last decade for visible wavelengths in the solid-state lighting revolution, and gave birth to several new applications. A similar revolution is expected in the deep-UV spectrum. Semiconductor light sources such as Light-Emitting Diodes (LEDs) and Lasers in the deep ultraviolet (UV) spectrum have versatile applications in water and air purification, in healthcare applications of biophotonic diagnostics and sterilization, in food preservation, in security and environmental monitoring and in industrial curing. The semiconductor material substrate of choice for deep-UV photonic devices is direct-bandgap AlN with an energy bandgap of ~6.2 eV (200 nm), and the active regions where photons are produced are various ternary compositional alloys of AlN with GaN of bandgap ~3.4 eV (365 nm).For deep-UV LEDs, quantum well active regions composed of AlGaN have been used to push the interband optical transition to high energies [1][2][3][4][5]. The internal quantum efficiency in high Al containing AlGaN Quantum Wells (QWs)/barrier structures is limited by the quantum confined stark effect (QCSE) [6][7][8], edge emission due to valence band structure re-ordering [9][10][11], combined with material defect (e.g. dislocation) induced non-radiative recombination. Compositional fluctuations of Al and Ga concentrations in ternary AlGaN alloy layers degrade efficient optical emission in the deep-UV range [12], and together with the other effects degrade the LED efficiency.Distinct from the alloy AlGaN layers, deep-UV emission down to 224 nm has been achieved in binary GaN/AlN heterostructures [13][14][15][16][17]. As a significant advantage, the polarization of the emitted photons in ultrathin GaN QWs and quantum dots/disks (QDs) is perpendicular to the c axis, making them propagate parallel to the c-axis [9,11]; this surface emission property is highly favorable for light extraction.We recently demonstrated deep UV LEDs [18-20] emitting as short as 232 nm by incorporating 2 monolayer (ML) thick GaN QDs in AlN barriers. As the height of the QD reduces and the oscillator strength increases [21], the radiative lifetime decreases significantly, increasing the internal quantum efficiency. Shortening the emission wavelength even deeper below 230 nm by utilizing GaN QDs embedded in AlN barriers will further enable applications in sensing and toxic gas detection applications. Tunable sub-230 nm deep-UV emission was demonstrated by Molecular Beam Epitaxy (MBE) growth of 2 ML GaN QDs using a modified Stranski-Krastanov (m-SK) growth method [22]. The m-SK technique uses thermal annealing of the 2 ML GaN quantum well structure sandwiched between AlN barriers. In this letter, we present an alternative approach to realize tunable sub-230 nm emission with higher internal quantum efficiency using SK growth of 2 ML GaN QD structures by MBE. Unlike the earlier work based on m-SK method, cont...

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“…The 4 nm AlN barriers were grown using migration enhanced epitaxy (MEE) [23] to ensure a smooth heterointerface between AlN and GaN by avoiding excess Al.…”

mentioning

confidence: 99%

Deep-UV emission at 219 nm from ultrathin MBE GaN/AlN quantum heterostructures

Islam

Protasenko

Lee

et al. 2017

Applied Physics Letters

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“…Methods used have included growth on vicinal surfaces to ensure step-flow growth; growth interruption to allow surfaces to anneal; and various photon and ionised particle irradiation techniques which provide energy to enhance surface migration. A simple and effective technique was recently invented (Horikoshi et al 1988) which greatly enhances the surface mobility at At Tc the migration length is of order of the step separation (after Dobson et al 1987).…”

Section: Migration Enhanced Epitaxymentioning

confidence: 99%

“…11) where Ns is deduced from the three dimensional crystallography. But also as NGa is increased, maxima in the oscillation recovery occur at NGa = 2Ns and 3Ns: it is thought that the excess Ga atoms form droplets which act as a source for two dimensional growth when the As is deposited (Horikoshi et al 1989). These droplets have been observed in RHEED images (Yamada et al 1989).…”

Section: Migration Enhanced Epitaxymentioning

confidence: 99%

The Growth of Semiconductor Thin Films Studied by RHEED

Price¹

1990

Aust. J. Phys.

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Recent developments in the growth of semiconductor thin films are reviewed. The emphasis is on growth by molecular beam epitaxy (MBE). Results obtained by reflection high energy electron diffraction (RHEED) are employed to describe the different kinds of growth processes and the types of materials which can be constructed. MBE is routinely capable of heterostructure growth to atomic precision with a wide range of materials including III-V, IV, II-VI semiconductors, metals, ceramics such as high Tc materials and organics. As the growth proceeds in ultra high vacuum, MBE can take advantage of surface science techniques such as Auger, RHEED and SIMS. RHEED is the essential in-situ probe since the final crystal quality is strongly dependent on the surface reconstruction during growth. RHEED can also be used to calibrate the growth rate, monitor growth kinetics, and distinguish between various growth modes. A major new area is lattice mismatched growth where attempts are being made to construct heterostructures between materials of different lattice constants such as GaAs on Si. Also described are the new techniques of migration enhanced epitaxy and tilted superlattice growth. Finally some comments are given On the means of preparing large area, thin samples for analysis by other techniques from MBE grown films using capping, etching and liftoff.

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“…However, HVPE of AlN has proved successful using AlCl3, which does not react with the quartz reactor at the growth temperatures [1]. In addition, we have reported that AlGaN ternary alloy can be grown by HVPE using GaCl-AlCl3-NH3 system [2]. In the presentation, a thermodynamic analysis of the HVPE of AlN using AlCl3 and AlGaN using AlCl3 and C87 Quantum dots (QDs) of nitride semiconductors have been studied intensively because of their usefulness for device applications.…”

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confidence: 99%

“…The time sequence of the opening of the shutter of a Ga effusion cell was used for the trigger signal to operate the mode change operation of nitrogen ICP -RF discharge. An activity modulation migration enhanced epitaxial growth (AM-MEE) method is prpposed as an application of the MEE [2]. In order to grow the high quality layers on a Si substrate the AM-MEE growth method was performed.…”

mentioning

confidence: 99%

Hydride vapor-phase epitaxy of AlN and AlGaN

Koukitu¹,

Kumagai²,

Murakami³

2008

Acta Cryst Sect A

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MSMicrosymposia experimental data to perform a three-dimensional bond density refinement of the Si(111)-7x7 surface. These two experimental techniques are quite complimentary as electron diffraction is rather more sensitive to the core-screening effects of bonding, while only the x-ray dataset is three dimensional (and is a direct transform of the local charge density). By utilizing a combinatorial ab initio Density Functional Theory (DFT) approach, we have developed a parameterized model for fitting valence charge density in silicon to experimental diffraction data which enhances performance, but adds no additional adjustable parameters. When bonding effects are properly accounted for, the improvement to the refinement of the overall structure is significant to >99% confidence (using a degree-of-freedom reduced Chi figure of merit), and site-specific perturbations due to adatom bonding at the surface are also possible. The experimental results will be compared to a full-potential, allelectron DFT structural relaxation of the Si (111) Recent theoretical and experimental results on the diffraction of x-rays near absorption edges of atoms (resonant diffraction) will be presented together with application to electronic and phonon properties of crystals (a review of earlier results can be found in [1]). In comparison with EXAFS, the resonant diffraction is more sensitive to the symmetry of atomic environment and to distortions of the electronic states of atoms in crystals. For example, the resonant forbidden reflections can be caused by opposite chirality of atomic positions in centrosymmetric crystals (observed in Fe2O3 and Cr2O3), or by phonon displacements of atoms (studied in detail for Ge and ZnO), or by the quantum jumps of hydrogen atoms in KH2PO4-type crystals. Symmetry consideration is accompanied by results of the muffin-tin and ab initio simulations. Experimental studies have been done in collaboration with synchrotron groups from Tsukuba, Grenoble, Hamburg, Daresbury, Oxfordshire, and Moscow. This work was supported by the Russian Foundation for Basic Research (project 07-02-00324).[1] V. E. Dmitrienko, K. Ishida, A. Kirfel, E. N. Ovchinnikova, Polarization anisotropy of X-ray atomic factors and 'forbidden' resonant reflections, Acta Crystallographica A61 (2005) The conditions for the reliable simulation of semiconductor surface structure and processes are formulated for GaN growth by Hydrogen Vapor Phase Epitaxy. The chemical state of the system is formulated within kinetic and thermodynamic picture. The GaN(0001) surface in ammonia-rich (N-rich and H-rich) environment is analyzed. The equilibrium state of GaN (0001) surface is considered using both formulations. Using ab-initio quantum mechanical density functional theory (QM DFT) SIESTA and VASP codes, it is proved that the thermodynamic approach, suggesting the mixed NH3-NH2 coverage is in accordance with the dynamic results, which show that ammonia is adsorbed molecularly on the surface. The resulting NH3 coverage is dynamically unstable with respe...

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Migration-Enhanced Epitaxy of GaAs and AlGaAs

Cited by 364 publications

References 20 publications

Deep-UV emission at 219 nm from ultrathin MBE GaN/AlN quantum heterostructures

Deep-UV emission at 219 nm from ultrathin MBE GaN/AlN quantum heterostructures

The Growth of Semiconductor Thin Films Studied by RHEED

Hydride vapor-phase epitaxy of AlN and AlGaN

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