Growth mechanism of atmospheric pressure MOVPE of GaN and its alloys: gas phase chemistry and its impact on reactor design

Matsumoto, Koh; Tachibana, Akitomo

doi:10.1016/j.jcrysgro.2004.08.115

Cited by 53 publications

(48 citation statements)

References 26 publications

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“…These results denote that the generation and growth of GaN cores in the gas phase are preferable to some extent. As shown in our previous work [4,5,14], however, parasitic reactions which enhance the chain reactions, e.g. TMG + DMG(NH 2 ) → (CH 3 ) 3 Ga 2 (CH 3 ) 2 (NH 2 ), disturb the crack-free crystal growth.…”

Section: Methodsmentioning

confidence: 63%

First‐principle study on crystal growth of Ga and N layers on GaN substrate

Doi

Maida

Kimura

et al. 2007

Phys. Status Solidi (c)

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GaN surfaces show several types of the surface growth depending on the surface structures. In this study, we have simulated some kind of initial states of GaN surface growth from the viewpoint of metal-organic chemical-vapor deposition (MOCVD). It is clarified that NH 3 molecules and N radicals can not fully terminate the (0001) Ga surface, and that chemical reactions between trimethylgallium and NH 3 in gas-phase is desirable to some extent because the products which contain GaN cores are immediately stabilized on the GaN(0001) surface.1 Introduction III-V nitride semiconductors have attracted much attention to be applied to several devices, light-emitting diodes, laser diodes, and photo detectors, during these 20 years [1,2]. A lot of trials and errors have been examined to fabricate GaN single crystal to satisfy the industrial requirements, although eliminating the defect concentrations is not easy. It is known that GaN surfaces show several types of the growth mechanism caused by the surface stability different between Ga and N surfaces [3]. In our previous studies, we discussed the parasitic reactions of trimethylgallium (TMG) and trimethylaluminum (TMA) in gas phase which disturb the growth of GaN and AlGaN single crystals [4,5]. Furthermore in this work, we investigate the growth mechanism of GaN single crystals from the view point of metal-organic chemical-vapor deposition (MOCVD) and analyze the relationship between the gas phase and surface reactions.

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Section: Methodsmentioning

confidence: 63%

First‐principle study on crystal growth of Ga and N layers on GaN substrate

Doi

Maida

Kimura

et al. 2007

Phys. Status Solidi (c)

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“…However, the growth rate is generally limited by parasitic chemical reactions initiated by trimethyl-aluminum (TMA) and ammonia (NH 3 ) precursors. [3][4][5][6][7][8] Creighton and Wang 6 investigated the early stages of the reaction between TMA and NH 3 using IR spectroscopy and density functional theory (DFT) calculations. They reported a parasitic reaction mechanism in which a TMA-NH 3 adduct was first formed and subsequently decomposed into amide and methane, finally producing amide oligomers.…”

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confidence: 99%

Chemical Reaction Pathways for MOVPE Growth of Aluminum Nitride

Inagaki

Kozawa

2015

ECS J. Solid State Sci. Technol.

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The chemical reaction pathways for metal-organic vapor phase epitaxial growth of aluminum nitride (AlN) were investigated using elementary reaction simulations and density functional theory calculations. We found that alkyl-aluminum amide (DMA-NH 2 ), which initiates parasitic chemical reactions such as oligomerization, is one of the major reactive species involved in AlN growth. The simulation results indicated that DMA-NH 2 is adsorbed on the surface, followed by the elimination of methane with no energy barrier. The results clarify the role of parasitic reactions and their products in the growth of AlN. Aluminum nitride (AlN) is an attractive semiconductor material due to its wide bandgap of 6.1 eV and high thermal conductivity. Moreover, AIN is commonly used as a buffer layer for the heteroepitaxial growth of gallium nitride (GaN) 2 because it has both a low lattice mismatch with and a similar thermal expansion coefficient to GaN. In AlN growth, metal-organic vapor phase epitaxy (MOVPE) is the most widely used technique because it is capable of large-area growth and because both the layer thickness and composition can be precisely controlled. However, the growth rate is generally limited by parasitic chemical reactions initiated by trimethyl-aluminum (TMA) and ammonia (NH 3 ) precursors.3-8 Creighton and Wang 6 investigated the early stages of the reaction between TMA and NH 3 using IR spectroscopy and density functional theory (DFT) calculations. They reported a parasitic reaction mechanism in which a TMA-NH 3 adduct was first formed and subsequently decomposed into amide and methane, finally producing amide oligomers. Thus, the chemical pathway through the TMA-NH 3 adduct is believed to cause the parasitic reactions that negatively impact AlN growth. However, the contribution of molecules derived from the parasitic reactions of AlN growth remains unclear, although several kinetic models that consider an AlN growth pathway through adduct-related molecules have been developed. [7][8][9] Therefore, in the present study, we investigated the possibility of a chemical reaction pathway through the TMA-NH 3 adduct using elementary reaction simulations and DFT calculations.Elementary reaction simulations were carried out to determine the reactive species using a kinetic model for AlN growth reported by Mihopoulos et al. 9 The basic concept of this growth mechanism is similar to that described by Creighton and Wang. 6 The kinetic model has 10 gas-phase and 7 surface reactions. A perfectly stirred reactor (PSR) was selected for the simulation. In the calculations assuming a PSR, the gas conditions were computationally-optimized by adjusting parameters such as residence time, pressure, and temperature. Additionally, it is assumed that the gas is homogeneous at the moment of gas supply. The residence time of the gas was set to 1 s, the pressure was set to 100 Torr, and the V/III ratio was set to 115. These values were determined by referencing previous reports by Amano 10,11 describing AlN growth with reduced parasit...

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“…Each wafer was also mechanically rotatable. The details of tri-gas injector were described in our previous paper [10] GaN and AlGaN layers were grown at atmospheric pressure throughout this study. All components inside the reactor were routinely cleaned afetr every growth run using an ex-situ dry-etching system (Taiyo Nippon Sanso Corp., DEX-100) to improve the yields of the epitaxy process.…”

Section: Methodsmentioning

confidence: 99%

Multiwafer atmospheric‐pressure MOVPE reactor for nitride semiconductors and ex‐situ dry cleaning of reactor components using chlorine gas for stable operation

Tokunaga¹,

Fukuda²,

Ubukata³

et al. 2008

Phys. Status Solidi (c)

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We describe an atmospheric‐pressure MOVPE reactor with a capacity of 2 inch by 10 or 3 inch by 8. In this reactor, the parasitic reaction of particulate generation is suppressed by adopting a high‐flow‐speed design. As a result of suppressing of the parasitic reaction, we have also grown GaN at a growth rate of more than 28 μm/hr at atmospheric pressure. It is also important to grow a heterostructure of Al‐containing alloys continuously to enable device applications, while maintaining the proper growth conditions for other layers such as GaN:Mg. An Al0.09Ga0.91N layer has been grown at a growth rate of 1 μm/h at atmospheric pressure. In the production environment, it is also essential to operate a reactor under a stable condition. To this end, we have adopted ex‐situ dry cleaning of all reactor components with deposits on them after every growth run. Dry cleaning was conducted using chemical etching of the deposit by chlorine gas in a hot tube reactor at about 800 °C. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Growth mechanism of atmospheric pressure MOVPE of GaN and its alloys: gas phase chemistry and its impact on reactor design

Cited by 53 publications

References 26 publications

First‐principle study on crystal growth of Ga and N layers on GaN substrate

First‐principle study on crystal growth of Ga and N layers on GaN substrate

Chemical Reaction Pathways for MOVPE Growth of Aluminum Nitride

Multiwafer atmospheric‐pressure MOVPE reactor for nitride semiconductors and ex‐situ dry cleaning of reactor components using chlorine gas for stable operation

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