Preparation of large GaN substrates

Motoki, Kensaku; Okahisa, Takuji; Nakahata, Seiji; Matsumoto, Naoki; Kimura, Hiroya; Kasai, Hitoshi; Takemoto, Kikurou; Uematsu, Koji; Ueno, Masaki; Kumagai, Yoshinao; Koukitu, Akinori; Seki, Hisashi

doi:10.1016/s0921-5107(02)00048-x

Cited by 39 publications

(26 citation statements)

References 19 publications

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Section: Resultscontrasting

confidence: 99%

“…This is quite different from the well known results of [2], where the Ga-rich conditions were assumed. These conditions are typical for the GaN growth by Plasma-Assisted Molecular Beam Epitaxy (PA-MBE) [2]. Adsorption of gallium chloride (GaCl) on GaN (0001) Adsorption of GaCl on GaN(0001) surface was calculated using the same approach for the two cases: N and NH 2 -covered surface.…”

Section: Resultscontrasting

confidence: 99%

“…(2) Adsorption energy of NH 3 molecule is higher than 2.5 eV, stabilizing the molecule and the surface and preventing its thermal desorption. (3) GaN (0001) surface is in N-rich state for both MOVPE and HVPE growth conditions.…”

Section: Discussionmentioning

confidence: 99%

“…The progress in the technology of the GaN based laser diodes (LDs) is not satisfactory which is related to ineffective p-type doping [1] and low crystalline quality of commercially available large GaN substrates [2]. Until now GaN single crystals of substrate crystallographic industrial standard of the dislocation density below 10 4 cm -2 , could be obtained by High Nitrogen Pressure Solution Growth (HNPSG) method [3].…”

Section: Introductionmentioning

confidence: 99%

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Modelling the growth of nitrides in ammonia‐rich environment

Krukowski¹,

Kempisty

Strąk

et al. 2007

Cryst. Res. Technol.

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Key words gallium nitride, hydrogen vapor phase epitaxy, metal organic vapor phase epitaxy, density functional theory. PACS 61.50.Ah, 81.10.Aj Surface properties and the principal processes at the growth of gallium nitride on GaN (0001) face in ammonia-based are modeled using DFT (density functional theory -SIESTA code) ab initio calculations and 2-d diffusion analysis. The GaN growth methods are: ammonia-source MBE, MOVPE, and also HVPE. The adiabatic trajectories, calculated for hydrogen-rich and hydrogen-free state of the GaN(0001) surface, include the adsorption of NH 3 , GaCl and HCl molecules and the desorption of Ga atoms. The adsorption of ammonia and GaCl has no energy barrier. Thus, in contrast to the results concerning Plasma-Assisted Molecular Beam Epitaxy (PA MBE), proving that the GaN(0001) surface remains in metal-rich state, these results indicate that, in the ammonia-rich environment, typical for HVPE and MOVP growth, the GaN(0001) surface remains in the nitrogen-rich state. In the case of HCl adsorption, the energy barrier depends on the surface coverage, and could reach 2.0 eV. The direct desorption of single Ga atom has the energy barrier, close to 7 eV. This indicates that Ga surface diffusion (growth controlling process) length is very large, leading to strong interaction of the step kinetics and the diffusion on the terraces. This interaction leads to double-step intertwined structures both in the case of dislocation-mediated spiral growth and in the step flow growth mode. These morphologies, proposed by the geometric arguments, are observed in the atomic force microscopy (AFM) scans of the GaN(0001) surface. Additionally we have compared the interaction energy of two hydrogen atoms obtained in the DFT SIESTA and the high precision Gaussian in coupled cluster singles, double and perturbation triples CCSD(T) approximation. Both approaches yielded virtually identical interaction energy confirming the validity of DFT analysis of ammonia-rich growth of GaN.

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Section: Resultscontrasting

confidence: 99%

Section: Resultscontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modelling the growth of nitrides in ammonia‐rich environment

Krukowski¹,

Kempisty

Strąk

et al. 2007

Cryst. Res. Technol.

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“…The progress in the technology of the GaN based laser diodes (LDs) is relatively slow that is in large part caused by ineffective p-type doping [1] and low crystalline quality of commercially available large GaN substrates [2]. GaN single crystals of substrate crystallographic industrial standard of the dislocation density below 10 4 cm −2 were obtained by High Nitrogen Pressure Solution Growth (HNPSG) method [3] and recently also by ammonothermal growth [4].…”

Section: Introductionmentioning

confidence: 99%

Review: GaN growth by ammonia based methods – density functional theory study

Krukowski¹,

Kempisty²,

Strąk³

2009

Cryst. Res. Technol.

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Key words gallium nitride, hydrogen vapor phase epitaxy, metal organic vapor phase epitaxy, density functional theory. PACS 61.50.Ah, 81.10.AjRecent results in Density Functional Theory (DFT) simulations of ammonia-based growth of gallium nitride on GaN (0001) are reviewed. These simulations are important to the following GaN growth methods that use ammonia as active nitrogen source: ammonothermal, MOVPE, HVPE and also ammonia-source MBE. In the simulations of GaN growth, the two main approaches were discussed: (1) equilibrium, based on chemical potentials of the components, and (2) dynamic, based on consideration of atomistic processes on the surface. These two approaches are unified by the kinetic procedure of determination of the chemical potential levels for nitrogen and hydrogen as a function of partial pressure of ammonia. Here the DFT modeling of GaN(0001) surface employing the technique of the simulation of subsurface electric field is described and employed. The results of DFT modeling include the ammonia and molecular hydrogen adsorption on GaN(0001) surface that allows to determine some basic features of ammonia-based growth of GaN. Dedicated to Prof. Wolfgang Neumann on the occasion of his 65th birthday

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