Validating gallium nitride growth kinetics using a precursor delivery showerhead as a novel chemical reactor

Parikh, Rinku P.; Adomaitis, Raymond A.; Aumer, M. E.; Partlow, Deborah P.; Thomson, D. B.; Rubloff, Gary W.

doi:10.1016/j.jcrysgro.2006.07.031

Cited by 12 publications

(9 citation statements)

References 17 publications

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“…The deposition of GaN is conduced typically at temperatures of 1000 °C, usually adopting ammonia and trimethylgallium (TMGa) as reactants with a V−III ratio (NH 3 /TMGa) higher than 1000, and hydrogen as the carrier gas. , Major problems encountered during the growth of high-quality films are represented both by the absence of a homoepitaxial substrate, so that films are usually deposited on sapphire, which has a lattice mismatch of 14% with GaN, and by the presence of severe parasitic gas-phase reactions. These undesired reactions lead to the formation of GaN gas-phase adducts and thus determine the nucleation of particles formed by several gallium, nitrogen, carbon, and hydrogen atoms. − Once generated, GaN powders can adsorb on the reactor walls or the growth surface, thus affecting the film quality, though this process is contrasted by thermal diffusion, which hinders the diffusion of heavy particles toward hot surfaces if a sufficient thermal gradient is present. The formation of gas-phase particles is an important technological problem because it is associated with the following: loss of precursors, which will not be available for deposition; fouling of the reactor, which must therefore be cleaned periodically; formation of stable intermediate species of relatively low molecular weight, thus only slightly affected by thermal diffusion, which might adsorb on the surface in positions that might not be epitaxial and thus give rise to the formation of defects, such as stacking faults …”

Section: Introductionmentioning

confidence: 99%

Theoretical Investigation of the Gas-Phase Kinetics Active during the GaN MOVPE

Moscatelli

Cavallotti

2007

J. Phys. Chem. A

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Quantum chemistry investigations have been performed to study the gas-phase chemistry active during the MOVPE of GaN when Ga(CH3)(3) and NH3, diluted in a H2 carrier gas, are used as precursors. Optimized molecular geometries, energies, and transition-state structures of gas-phase species have been determined with density functional theory at the B3LYP/6-311+g(d,p) level. On the basis of the similarity with the soot formation mechanism active during hydrocarbon combustion, we propose that in this system a gas-phase chemistry is active and its reactivity is enhanced by a radical chain mechanism started from methyl radicals. Initiation reactions are surface processes or the pyrolysis of Ga(CH3)(3). A propagation mechanism composed of fast radical reactions, most of which without an activation energy, was identified, and kinetic constants were determined for each step. The proposed mechanism is able to describe the formation of large GaN adducts formed by up to three R-Ga-NH units. These molecules can give fast cyclization reactions that lead to the formation of six-membered cyclic species, which, similar to benzene for combustion, are thermodynamically stable in vast temperature and pressure ranges and can thus be considered as the first GaN nuclei. We also found that the presence of H2 as a carrier gas can greatly enhance the rate of formation of gas-phase particles because it is a major source of atomic hydrogen, a promoter of gas-phase reactivity.

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Section: Introductionmentioning

confidence: 99%

Theoretical Investigation of the Gas-Phase Kinetics Active during the GaN MOVPE

Moscatelli

Cavallotti

2007

J. Phys. Chem. A

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“…The high growth temperatures used in the growth of nitrides would lead to the conclusion that this adduct would dissociate before some intramolecular reaction. These reactions have driven the redesign of conventional MOVPE reactors to minimize these gas phase reactions [136][137][138][139][140]. These reactions have driven the redesign of conventional MOVPE reactors to minimize these gas phase reactions [136][137][138][139][140].…”

Section: Reactions Between Precursorsmentioning

confidence: 99%

Metal Organic Vapor Phase Epitaxy Chemical Kinetics

Kuech

2015

Handbook of Crystal Growth

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“…A reaction model describing the growth of GaN from TMG and ammonia is adopted in the papers . Rate parameters for all gas phase reactions are given in Table .…”

Section: Mathematical Modelsmentioning

confidence: 99%

Systematic study of epitaxy growth uniformity in a specific MOCVD reactor

Fang

Zhang

Pan

et al. 2014

Crystal Research and Technology

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Gallium nitride (GaN) is a direct bandgap semiconductor widely used in bright light‐emitting diodes (LEDs). Thin‐film GaN is grown by metal‐organic chemical vapour deposition (MOCVD) technique. Reliability, efficiency and durability of LEDs are influenced critically by the quality of GaN films. In this report, a systematic study has been performed to investigate and optimize the growth process. Fluid flow, heat transfer and chemical reactions are calculated for a specific close‐coupled showerhead (CCS) MOCVD reactor. Influences of reactor dimensions and growth parameters have been examined after introducing the new conceptions of growth uniformity and growth efficiency. It is found that GaN growth rate is mainly affected by the concentration of (CH3)3Ga:NH3 on the susceptor, while growth uniformity is mainly influenced by the recirculating flows above the susceptor caused by natural convection. Effect of gas inlet temperature and the susceptor temperature over the growth rate can be explained by two competing mechanisms. High growth efficiency can be achieved by optimizing the reactor design.

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Validating gallium nitride growth kinetics using a precursor delivery showerhead as a novel chemical reactor

Cited by 12 publications

References 17 publications

Theoretical Investigation of the Gas-Phase Kinetics Active during the GaN MOVPE

Theoretical Investigation of the Gas-Phase Kinetics Active during the GaN MOVPE

Metal Organic Vapor Phase Epitaxy Chemical Kinetics

Systematic study of epitaxy growth uniformity in a specific MOCVD reactor

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