Facets Formation Mechanism of GaN Hexagonal Pyramids on Dot-Patterns via Selective MOVPE

Hiramatsu, Kazumasa; Kitamura, Shota; Sawaki, Nobuhiko

doi:10.1557/proc-395-267

Cited by 18 publications

(5 citation statements)

References 9 publications

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“…Figure 4 displays Raman spectra of a 10 µm high GaN pyramid. The structure of the selectively epitaxially grown sample is depicted in the inset, the growth details are given elsewhere [32,33]. The spectra were recorded spatially resolved with an excitation energy of 514.5 nm at 4.2 K in different sample depths including the top and the GaN-sapphire interface.…”

Section: Configurationmentioning

confidence: 99%

Lattice dynamics in GaN and AlN probed with first‐ and second‐order Raman spectroscopy

Haboeck

Siegle

Hoffmann

et al. 2003

phys. stat. sol. (c)

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We present a selection of our contributions to basic research on the lattice dynamical properties of group-III nitrides and their alloys. We used first-order Raman scattering to determine the zone-center phonons and their dependence on structural attributes such as stress, chemical composition, impurities, and doping. Results on the angular dispersion of the polar modes, strain distribution, coupled LO-phonon plasmon modes, multi-mode behavior in Al x Ga 1-x N, and the quantitative determination of the phase purity of cubic and hexagonal GaN are shown. Second-order Raman-scattering experiments on GaN and AlN provide information on the vibrational states throughout the entire Brillouin zone. Based on a comparison of experimental data and calculated phonon-dispersion curves we assigned the observed structures to particular phonon branches and points in the Brillouin zone. We also discuss the behavior of the optical modes under large hydrostatic pressure. 1 Introduction During the last decade group-III nitrides have been an object of increasing research because of their interesting physical properties such as an adjustable band gap (1.9 eV to 6.2 eV) by varying the composition of the alloys [1] and application as basic materials for optoelectronic devices working in the blue and ultraviolet spectral region [2][3][4]. In particular GaN and AlN can withstand high temperatures and have large piezoelectric constants which makes them suitable for applications in highfrequency devices, sensors and low-dimensional structures [5,6].Although basic information about group-III nitrides e.g. crystal-and band structure have been available for a decade several details still remained unclear. In the following review of our work we present results of first-and second-order Raman investigations on various GaN, AlN, and Al x Ga 1-x N samples and point out some remarkable details of the structural and optical properties of these materials.

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Section: Configurationmentioning

confidence: 99%

Lattice dynamics in GaN and AlN probed with first‐ and second‐order Raman spectroscopy

Haboeck

Siegle

Hoffmann

et al. 2003

phys. stat. sol. (c)

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“…Kitamura et al [2,10] fabricated GaN hexagonal pyramids on dot-patterned GaN/sapphire substrates with a 5 µm diameter and a 10 µm space as shown in figure 2 [2]. Each structure comprises a hexagonal pyramid covered with six {1 101} facets.…”

Section: Growth and Characterizationmentioning

confidence: 99%

Epitaxial lateral overgrowth techniques used in group III nitride epitaxy

Hiramatsu

2001

J. Phys.: Condens. Matter

Self Cite

101

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Selective-area growth (SAG) and epitaxial lateral overgrowth (ELO) techniques used in group III nitride epitaxy are reviewed. Structurally controlled GaN in line patterns and dot patterns was obtained by using the SAG technique. This structural control technique has been applied to field emitters, waveguides, facet lasers and low-dimensional quantum structures. The ELO technique was originally proposed as a way to reduce dislocation density in epitaxial GaN layers and various ELO techniques have been developed recently. For example, facet-controlled ELO (FACELO) is one of the attractive techniques available for reducing dislocation density. The dislocation density is dramatically reduced to of the order of 105-6 cm-2 with good reproducibility. In this article, SAG and ELO techniques related to nitride epitaxy and applications to optical and electronic devices are reviewed. Production of GaN hexagonal pyramids on dot-patterned GaN/sapphire substrates and the FACELO technique are also described as examples of the SAG and ELO techniques.

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“…Using metalorganic vapor phase epitaxy ͑MOVPE͒, selective growth of GaN and AlGaN on linearly patterned GaN͑0001͒/sapphire substrate 7 and the growth of threedimensionally controlled structures have been reported. 8,9 For the sample in our present discussion, a 2-m-thick GaN͑0001͒ was first grown on a sapphire substrate ͓on axis ␣-Al 2 O 3 ͑1120͔͒ using an AlN buffer layer. A 50-60 nm thick SiO 2 mask was patterned by photolithography and subsequently etched to form hexagonal windows.…”

mentioning

confidence: 99%

Stress analysis of selective epitaxial growth of GaN

Liu¹,

Hoffmann

Siegle

et al. 1999

Applied Physics Letters

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Stress distributions in selectively overgrown self-organized GaN hexagonal pyramids have been analyzed by continuum elasticity theory. This has been carried out using the values for the moduli of elasticity found in the literature and an effective lattice mismatch between the GaN and the substrate that was determined from the Raman shift of the GaN buffer layer. The results of compressive stress in the buffer layer, tensile stress on the lower half of the pyramids' facet surface, and full relaxation for approximately the upper 2/3 of the pyramids are in satisfactory agreement with the experimental observations that were deduced from cathodoluminescence microscopy and micro-Raman spectroscopy.

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Facets Formation Mechanism of GaN Hexagonal Pyramids on Dot-Patterns via Selective MOVPE

Cited by 18 publications

References 9 publications

Lattice dynamics in GaN and AlN probed with first‐ and second‐order Raman spectroscopy

Lattice dynamics in GaN and AlN probed with first‐ and second‐order Raman spectroscopy

Epitaxial lateral overgrowth techniques used in group III nitride epitaxy

Stress analysis of selective epitaxial growth of GaN

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