Influence of polymer formation on metalorganic vapor-phase epitaxial growth of AlN

Uchida, Takeshi; Kusakabe, Kazuhide; Ohkawa, Kazuhiro

doi:10.1016/j.jcrysgro.2007.01.022

Cited by 34 publications

(37 citation statements)

References 20 publications

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“…A modelling of reaction pathways in a TMAl/NH 3 /H 2 system including parasitic and polymeric reactions was proposed for CFD simulation, and AlN growth rates calculated were in good agreement with experimental ones [12]. The CFD simulation is effective to understand gas-phase chemistry and growth mechanism in an MOVPE reactor.…”

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confidence: 58%

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Analysis of pulsed injection of precursors in AlN‐MOVPE growth by computational fluid simulation

Nakamura¹,

Hirako

Ohkawa

2010

Phys. Status Solidi (c)

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We report computational analysis of gas‐phase states and main reaction pathways under AlN metalorganic vapor‐phase epitaxy (MOVPE) by pulsed injection (PI) method of precursors. Interval times of 0–2 s were inserted between trimethylaluminum (Al(CH3); TMAl) and ammonia (NH3) supply phases to suppress parasitic reactions. In the cases of the interval time of 0 s, polymers and Al‐N molecules were dominant species due to parasitic reaction, and the growth species was Al‐N molecules generated by TMAl:NH3 pyrolysis. When an interval time was inserted between TMAl and NH3, mixing of TMAl and NH3 were suppressed. Al and NH2 generated from each precursor were dominant species. The main reaction pathway changed from TMAl:NH3 pyrolysis into TMAl pyrolysis with increasing the interval time. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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confidence: 58%

“…We have studied reaction pathways of GaN-and AlNMOVPEs by computational fluid dynamic (CFD) simulation [9][10][11][12]. A modelling of reaction pathways in a TMAl/NH 3 /H 2 system including parasitic and polymeric reactions was proposed for CFD simulation, and AlN growth rates calculated were in good agreement with experimental ones [12].…”

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confidence: 75%

Analysis of pulsed injection of precursors in AlN‐MOVPE growth by computational fluid simulation

Nakamura¹,

Hirako

Ohkawa

2010

Phys. Status Solidi (c)

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“…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.…”

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confidence: 99%

“…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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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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“…One representative example is MOVPE AlN growth using TMAl and NH 3 sources, where the AlN incorporation efficiency falls drastically to almost zero as pressure is increased to ∼400 mbar. 43,44 Thus, in this series two sets of experiments were performed; one at ceiling temperature of 600…”

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confidence: 99%

Incorporation Behaviors of In and Ga in the Two-Heater MOVPE Growth of InGaN Films

Cheng

Lee

et al. 2016

ECS J. Solid State Sci. Technol.

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Incorporation behaviors of In and Ga of InGaN films grown by the two-heater metal-organic vapor-phase epitaxial horizontal reactor is investigated by varying growth parameters, such as the substrate temperature, ceiling temperature and reactor pressure. Two In loss mechanisms are observed by the analysis of the concentration and temperature profiles in the deposition zone. The gas-phase parasitic-loss mechanism (activation energy ∼ 34.2 ± 0.1 kcal/mol) is significant in the ceiling temperature T ceil ≥ 800 • C and at substrate temperature (T sub ) of 600 • C. The decomposition-loss mechanism, which arises from In desorption on the growing surface, is significant in T sub > 625 • C region. The desorption activation energy obtained is 28.0 ± 0.1 kcal/mol, which is close to that of . This suggests the In decomposition-loss mechanism in InGaN growth does not differ substantially from that in binary InN growth. On the other hand, the gas-phase parasitic-loss mechanism of Ga is negligible in the growth condition that we have explored. Exception is found for reactor pressure at T ceil = 950 • C, where both factors advantageous and disadvantageous to Ga incorporation are unambiguously observed. We have proposed explanation for the above observation. The promising electronic and optical properties of InGaN alloy, such as high two-dimensional electron gas (2DEG) electron mobility, wide tunability of photon emission energy from 0.7 to 3.4 eV, have given rise to numbers of applications in the past decade. These include high power and high electron mobility transistor (HEMT), visible light emitting devices, tandem solar cell, and solid state lighting.1-7 To realize, a method that capable of growing device-quality III-V nitrides is essential. Among all growth methods, metal-organic vapor-phase epitaxy (MOVPE) has proved itself to be the most reliable and major tool to produce these devices with mass-production feasibility. However, difficulties arise for this method in preparing high In content In x Ga 1−x N film (x > 30%) with acceptable optical and electrical properties. This stems mainly from the intrinsic properties of material itself, such as thermal instability of InN, wide miscibility gap, and large thermal-and lattice-mismatch between InGaN layer and underlying GaN base layer, and poor cracking efficiency of NH 3 . These lead to generations of considerable amounts of nitrogen vacancies, pits, In-rich clusters and/or structure defects in the film to deteriorate its material properties. [8][9][10][11][12][13][14][15][16][17] In our previous work, we have employed a so-called the two-heater MOVPE horizontal reactor, consisting of a pair of paralleled ceiling and substrate heaters, 18 to grow InGaN films. We demonstrated its ability in preparing high In-content thick InGaN films with emission wavelength extended into infrared color region, and more importantly exhibiting good optical-quality and high spectral uniformity. For instance, a sample with x = 0.40 In x Ga 1−x N film has a mean emission wavelength of 808 ± 6 nm a...

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Influence of polymer formation on metalorganic vapor-phase epitaxial growth of AlN

Cited by 34 publications

References 20 publications

Analysis of pulsed injection of precursors in AlN‐MOVPE growth by computational fluid simulation

Analysis of pulsed injection of precursors in AlN‐MOVPE growth by computational fluid simulation

Chemical Reaction Pathways for MOVPE Growth of Aluminum Nitride

Incorporation Behaviors of In and Ga in the Two-Heater MOVPE Growth of InGaN Films

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