A comparative study of Ga(CH3)3 and Ga(C2H5)3 in the mombe of GaAs

Pütz, Norbert; Heinecke, H.; Heyen, M.; Balk, P.; Weyers, M.; Lüth, H.

doi:10.1016/0022-0248(86)90118-1

Cited by 179 publications

(17 citation statements)

References 13 publications

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“…There is, in fact, still disagreement over such fundamental questions as the relative importance of homogeneous and heterogeneous reactions in atmospheric pressure MOCVD, 12,\3 In early MOMBE studies, TEGa was found to yield lower residual carbon concentrations (10 14 _10 16 cm -3) in GaAs films than could be obtained using TMGa (10 19 _10 20 cm-3 ). 15,16 This has been widely attributed to ,8-hydride elimination of C 2 H4 when TEGa is used. 17 , 18 This reaction occurs in the gas phase (from secondary decomposition of Ga (C 2 H5 ) 2 after TEGa has partially decomposed by loss of one ethyl group from simple bond cleavage), 19 and has recently been reported to take place on the GaAs surface (also from secondary decomposition of dissociatively chemisorbed TEGa).…”

Section: Introductionmentioning

confidence: 99%

Kinetics of thermal decomposition of triethylgallium, trimethylgallium, and trimethylindium adsorbed on GaAs(100)

McCaulley

Shul

Donnelly

1991

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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We report studies of the kinetics of thermal decomposition of triethylgallium (TEGa), trimethylgallium (TMGa), and trimethylindium (TMIn) adsorbed on GaAs(100) in ultrahigh vacuum. The adsorbed layers were prepared by dosing GaAs(100) at room temperature, to either saturated coverage or coverages below saturation. The relative coverage of carbon was monitored by x-ray photoelectron spectroscopy (XPS) as the substrate temperature was slowly increased (0.6–3.2 °C/min). Products were detected at faster heating rates (0.7–6 °C/s) with a differentially pumped quadrupole mass spectrometer. The substrate temperature was measured by infrared laser interferometric thermometry. The kinetic analysis also makes use of XPS and mass spectrometric data on laser-induced, rapid thermal decomposition (heating rates of ∼1011 °C/s ). TEGa dissociatively chemisorbs on GaAs(100) at room temperature. Heating the substrate from room temperature to ∼500 °C results in desorption of a Ga–alkyl at low temperature, ascribed mostly to diethylgallium (DEGa) and possibly some TEGa. At higher temperature, C2H4 and C2H5 desorb in parallel after most of the Ga–alkyl has desorbed. The hydrocarbon desorption is described well by simple first order kinetics with an activation energy, Eact=32±4 kcal/mol, and a pre-exponential A factor of 2.5×1010±1.5 s−1. Ga–alkyl desorption is more complicated; the Arrhenius parameters for assumed first order desorption exhibit strong coverage dependences. A fit to all the data was obtained for A=5×108 s−1 and Eact=18 kcal/mol at saturated coverage, with a large decrease in Eact (or increase in A) with decreasing coverage. TMGa decomposes to yield a Ga–alkyl desorption product (either dimethylgallium, TMGa, or a mixture of the two) at low temperature, and CH3 at higher temperature. CH3 desorption has a first order activation energy of 43±2 kcal/mol for an assumed A factor of 1×1013 s−1. For the Ga–alkyl, A=108 s−1 and Eact=19 kcal/mol, with a coverage dependence similar to DEGa desorption from TEGa decomposition. TMIn undergoes a methyl exchange reaction on GaAs(100). Upon heating above room temperature, a Ga–alkyl desorbs first, followed by desorption of CH3 at higher temperature. The Ga–alkyl has with the same cracking pattern as observed for TMGa decomposition. No In–alkyls desorb, and In desorption does not occur until all carbon-containing species desorb. CH3 starts to desorb at lower temperature than for TMGa decomposition. Assuming an A factor of 1×1013 s−1, CH3 desorption over the observed wide temperature range indicates a range of activation energies from 33–43 kcal/mol. Ga–alkyl desorption is similar to that observed during TMGa decomposition. At saturated coverage, A=108 and Eact=17 kcal/mol. However, the coverage dependence is not as strong as for TMGa, so that Ga–alkyl desorption peaks at lower temperature for TMIn. Decomposition mechanisms for these group-III metal alkyls are discussed, along with implications for growth of III–V compound semiconductor films from these precursors by chemical vapor deposition and molecular beam techniques.

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Section: Introductionmentioning

confidence: 99%

Kinetics of thermal decomposition of triethylgallium, trimethylgallium, and trimethylindium adsorbed on GaAs(100)

McCaulley

Shul

Donnelly

1991

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…Furthermore, the high surface In/In-methyl coverage helps facilitate the formation and desorption of Ga-alkyl species by rapid alkyl exchange (ethyl with methyl) in a similar manner to that previously observed with the use of mixed alkyl precursors [15][16][17][18]. As physisorbed In and In-methyl species ride on the surface, methyl ligands strongly bond to excess Ga atoms made available via facile b-elimination [24,25]. The surface layer has been shown to enhance desorption of Ga-alkyls in the case of In covered GaAs [26] and InGaAs with TMIn [27].…”

Section: Discussionmentioning

confidence: 75%

Mixed alkyl exchange and exploitable surface interactions in InGaN by NH3-based metal organic molecular beam epitaxy

Pritchett¹,

Henderson²,

Billingsley³

et al. 2008

Journal of Crystal Growth

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“…While Zn can be incorporated by introducing precursors such as diethylzinc (DEZn), this dopant diffuses even more rapidly than Be [95 -97]. Fortunately, with the introduction of metalorganic precursors to the UHV environment it was found that significant carbon, and hole concentrations, could be introduced through the use of carbon-bonded gallium compounds like trimethylgallium (TMGa) [98][99][100][101][102].…”

Section: Carbon Doping During Growth From Molecular Beamsmentioning

confidence: 99%

“…Because a carbon atom is significantly smaller than the As atom it replaces on the group V sublattice, heavily carbon-doped material generally exhibits a reduction in the lattice constant [101,102,134], As …”

Section: Materials Qualitymentioning

confidence: 99%

Carbon-impurity incorporation during the growth of epitaxial group III?V materials

Abernathy

Hobson

1996

J Mater Sci: Mater Electron

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This paper is a review of the incorporation and behaviour of carbon in group III-V materials. Both vapour phase epitaxy and growth in ultra high-vacuum environments are covered. Particular attention is given to the factors which influence the carbon-uptake rate such as the growth temperature, ratio of group V to group III materials and parasitic interaction with other species at the growth front. Among the latter, the role of hydrogen is crucial not only to the understanding of the incorporation of carbon but also to its behaviour in the lattice. Consequently, this issue is thoroughly discussed for both growth methods. Potential sources for the introduction of carbon to the growth front are also compared in the light of their utility for obtaining high well-confined acceptor Profiles, such as are required in the latest-generation electronic and photonic devices. Finally, the material quality and dopant stability which can be obtained with carbon-doped materials will be briefly reviewed and, where possible, contrasted with that which can be obtained with other p-type dopants.

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A comparative study of Ga(CH3)3 and Ga(C2H5)3 in the mombe of GaAs

Cited by 179 publications

References 13 publications

Kinetics of thermal decomposition of triethylgallium, trimethylgallium, and trimethylindium adsorbed on GaAs(100)

Kinetics of thermal decomposition of triethylgallium, trimethylgallium, and trimethylindium adsorbed on GaAs(100)

Mixed alkyl exchange and exploitable surface interactions in InGaN by NH3-based metal organic molecular beam epitaxy

Carbon-impurity incorporation during the growth of epitaxial group III?V materials

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