Triethylarsine Research Articles

Efficiency of arsenic and phosphorus precursors investigated by reflectance anisotropy spectroscopy

The efficiency of several alternative group-V precursors was measured throught the As or P related structures in the reflectance anisotropy spectra from (001) surfaces of GaAs and InP. As arsenic precursors were investigated: arsine (AsH 3), tertiarybutylarsine (tBAsH 2) and triethylarsine (TEAs). The strength of the As-related feature at 2.5 eV in the reflectance anisotropy spectroscopy (RAS) spectrum of the typical metalorganic vapour phase epitaxy (MOVPE) pregrowth surface GaAs(001)-c(4 × 4) was measured as a function of precursor partial pressure and temperature. From these measurements, a relative efficiency for the arsenic supplied to the surface for the different precursors can be given. A higher efficiency of tBAsH 2 as compared to AsH 3 at 723 and 823 K, but equal efficiencies at 923 K, for both compounds are observed. For TEAs at lower temperatures (723 to 823 K), a new RAS spectrum different from the one for the c(4 × 4) is obtained. This reveals a surface different from the As double layer due to TEAs derivatives absorbed on the surface. At higher temperatures (923 K), a c(4 × 4)-like RAS spectrum is obtained indicating that at this temperature predominantly As is supplied from TEAs to the surface. Using both TEAs and AsH 3 simultaneously, the additional adsorbate structure disappears also at lower temperatures. This effect is attributed to the reaction of atomic hydrogen, derived from arsine, with the organic TEAs derivatives. The efficiencies of the alternative P precursors were evaluated through the P-related peak at 2.7 eV in the RAS spectrum of the phosphorus-rich InP(001)-(2 × 4). At a temperature of 873 K, the precursor tertiarybutylphosphine tBPH 2 revealed a much higher P efficiency than PH 3. In contrast, with tetraethyldiphosphine (TEDP) no P-rich (2 × 4)-like spectrum could be obtained but rather an In-rich (4 × 2) spectrum was indicated. This reveals a much lower P efficiency for TEDP than for two other P precursors. Accordingly, TEDP seems to be less well suited for MOVPE of P-containing compounds than tBPH 2.

Metalorganic molecular beam epitaxy growth of GaAs on patterned GaAs substrates

GaAs layers were grown on etch-patterned (100) GaAs substrates by MOMBE (metalorganic molecular beam epitaxy) using TEGa (triethylgallium) and thermally cracked TEAs (triethylarsine). Morphology and orientation dependencies of the grown facets on the growth temperature (400–630°C) and V/III ratio (2–4) are investigated. Good morphology of grown layers was obtained on (111)A side facets at a low V/III ratio of 3 and low growth temperatures of 450–500°C. We also found strong evidence that the formation of facets is not only governed by the migration of Ga precursors and/or Ga atoms, but also by a preferential catalytic decomposition of Ga precursors on the facet edges.

Study of the compositional control of the antimonide alloys InGaSb and GaAsSb grown by metalorganic molecular beam epitaxy

MOMBE (metalorganic molecular beam epitaxy) growth characteristics of Sb containing ternary alloys, InGaSb, and GaAsSb are investigated. In the growth of InGaSb using TEGa (triethylgallium), TMIn (trimethylindium), and Sb4 (elemental antimony), the enhanced desorption of methyl-In molecules at a substrate temperature Tsub of around 500 °C as well as the enhanced desorption of ethyl-Ga molecules at around 515 °C are observed. They are due to the weak bond strength of antimonide compounds. Furthermore, the decrease of Ga solid composition with increasing Sb4 flux and the increase of GaSb partial growth rate with TMIn flow rate are also observed at as high as 500 °C. This is caused by the fact that the site blocking effect of excess Sb atoms exists up to higher Tsub. In the growth of GaAsSb using TEGa, TEAs (triethylarsine), and TESb (triethylstibine), the Sb composition versus TESb/(TEAs+TESb) curve exhibits a bowing characteristic, which is similar to that in the MOVPE (metalorganic vapor phase epitaxy) growth and is different from that in the MBE (molecular beam epitaxy) growth. Mass transport properties of Sb molecules in the MOMBE are considered to be similar to that in the MOVPE. It is found that the Tsub dependence of Sb composition is much weaker than that in the MBE, which is a superior point of MOMBE in the growth of antimonide alloys.

MOMBE growth characteristics of antimonide compounds

This paper describes the MOMBE (metalorganic molecular beam epitaxy) growth characteristics of antimonide compounds using TMIn (trimethylindium), TEGa (triethylgallium) and TIBAl (triisobutylaluminium) as group III sources, and As 4, Sb 4, TEAs (triethylarsine) and TESb (triethylstibine) as group V sources. Large differences in the growth characteristics of GaAs and GaSb MOMBE are observed. These are explained, using a theoretical consideration of the growth mechanism, by the difference in the effective surface coverage of excess As and Sb atoms during the growth. The use of TEAs and TESb instead of As 4 and Sb 4 alters the growth rate variation of both GaAs and GaSb with substrate temperature ( T sub), which results from the interaction of alkyl Ga species with the alkyl radicals coming from the thermally cracked TEAs and TESb. The alkyl exchange reaction process is observed in the growth of AlGaSb using TIBAl and TEGa, where the incorporation rate of Al is suppressed by the coexistence of TEGa on the growth surface, in the low T sub region. This is caused by the formation of an ethyl-Al bond which is stronger than the isobutyl-Al bond. The composition and the growth rate variations of InGaSb with T sub are similar to those of InGaAs, which are closely related to the MOMBE growth process and are quite different from those of MBE (molecular beam epitaxy) and MOVPE (metalorganic vapor phase epitaxy) growth. In the MOMBE growth of InAsSb and GaAsSb using TEAs and TESb, the composition variation with T sub is weaker than that of MBE. This is a superior point of MOMBE growth for the composition control. The electrical and optical properties of MOMBE grown films as well as the quantum well structures are also described.

Epitaxial growth of GaAs and GaN by gas source molecular beam epitaxy using organic group V compounds

GaAs and GaN epilayers were grown on GaAs substrates by gas source molecular beam epitaxy technique using triethylarsine (TEAs) and diethylarsine (DEAsH) as As sources, and dimethylhydrazine (DMHy) as an N source. It was found that GaAs grows layer by layer even when organic arsine molecular sources are used. Cubic GaN was found to grow epitaxially on sufficiently nitrided surfaces of GaAs (001) substrates, in contrast with the growth of hexagonal GaN on GaAs (111) surfaces. It was also found that nitridation of GaAs surfaces does not occur when DEAsH and DMHy beams are supplied onto the GaAs substrates, simultaneously. Thus, GaN/GaAs multilayers were obtained only by intermittent supply of a DEAsH beam.

Mechanism of arsenic incorporation and electrical properties in CdTe layers grown by metalorganic vapor phase epitaxy

The As doping mechanism in (100) CdTe layers grown on (100) GaAs by atmospheric-pressure metalorganic vapor phase epitaxy was studied. Triethylarsine (TEAs) was used as a dopant source. The source materials used were dimethylcadmium (DMCd) and diethyltelluride (DETe). The As incorporation was enhanced by decreasing the DETe flow rate under a fixed DMCd flow condition, and by lowering the growth temperature. Assuming 100% activation of As, the As incorporation efficiency was estimated to be about 0.1%. The As incorporation was dominated by the sticking rate of the As species onto the Cd species. The hole concentration was controlled from 2×1015 to 3×1016 cm−3 in proportion to the TEAs flow rate below 1×10−7 mol/min. Those doped layers showed hole mobilities as high as 75 cm2/V s. Low-temperature photoluminescence (PL) studies revealed that a neutral-acceptor bound-exciton at 1.5901 eV is due to a substitutional As acceptor on the Te site. The As ionization energy was about 90 meV from the PL and electrical measurements.

Mechanism of arsenic incorporation in MOVPE growth of CdTe layers

The mechanism of As incorporation in CdTe layers grown by atmospheric-pressure metalorganic vapor phase epitaxy (MOVPE) is reported. Triethylarsine (TEAs) was used as a dopant source. The As incorporation decreased with the DETe flow rate under a fixed DMCd flow condition. On the other hand, the As incorporation increased as the growth temperature was decreased form 425 to 375°C. The As incorporation efficiency for TEAs was estimated to be about 0.1%, which is nearly equal to that for AsH 3. Since the pyrolytic temperature for TEAs is much lower than for AsH 3, these results indicate that the As incorporation is not dominated by the pyrolitic efficiency of the dopant source, but by the sticking rate of As species onto Cd species.

Radical reactions in pyrolysis of triethylarsine and diethylarsine

Pyrolysis of triethylarsine (TEAs) and diethylarsine (DEAsH) has been studied at atmospheric pressure in a flow tube reactor using mass spectrometry. He and D 2 were selected as the carrier gases to determine the ambient effects and to isotopically label the pyrolysis products. For some experiments, supplemental C 2H 5 radicals, produced from pyrolysis of a co-reactant azoethane ((C 2H 5) 2N 2), were added to investigate the role of C 2H 5 in the pyrolysis reactions of the ethylarsines. A significant ambient effect was observed for pyrolysis of TEAs, but not for DEAsH. The pyrolysis of DEAsH was enhanced by adding C 2H 5 radicals while the TEAs pyrolysis was nearly unaffected. DEAsD, rather than DEAsH, was a product for TEAs pyrolysis in D 2; however, the DEAsH pyrolysis produced TEAs in either ambient. This demonstrates that the β-elimination reaction is not a major step. Instead, radical reactions are more likely to dominate the pyrolysis process. Reaction mechanisms for pyrolysis of TEAs and DEAsH in both ambients have been proposed. The rate constants for the reactions involved were determined. In addition, consistency between the proposed reaction pathways and the experimental data has been examined using computer modelling.

MOMBE growth of GaSb and InAsSb using triethylstibine and triethylarsine

We report metalorganic molecular beam epitaxial (MOMBE) growth of GaSb and InAsSb using triethylgallium (TEGa), trimethylindium (TMIn), triethylstibine (TESb), and triethylarsine (TEAs). For GaSb growth, the maximum growth rate is observed at a substrate temperature of 500°C. This is associated with the use of TESb instead of solid Sb, where the alkyl species coming from thermally cracked TESb also play important roles in the pyrolysis of TEGa. For InAsSb growth, it is found that pyrolysis of TMIn at substrate temperatures below 400°C is decomposition limited. Precise control of solid composition for InAs 1−xSb x in the range of 0≤ χ≤0.6 is confirmed in the temperature range from 400 to 500°C.

Comparative pyrolysis studies of ethylarsines

The pyrolysis of triethylarsine (TEAs), diethylarsine (DEAsH), and monoethylarsine (MEAsH 2) has been studied at atmospheric pressure in a flow tube reactor using mass spectrometry. He and D 2 were selected as the carrier gases to determine ambient effects and to isotopically label the pyrolysis products. For some experiments, supplemental C 2H 5 and CH 3 radicals, produced from pyrolysis of the co-reactants azoethane ((C 2H 5) 2N 2) and azomethane ((CH 3) 2N 2), were added to investigate the roles of C 2H 5 and CH 3 in the reactions. Significant D 2 effects have been observed for pyrolysis of TEAs but not for DEAsH and MEAsH 2. Pyrolysis of the latter could be enhanced by adding C 2H 5 radicals while the TEAs was nearly unaffected. With the presence of supplemental CH 3 radicals, 85% decomposition was induced for each precursor. The products included DEAsD, rather than DEAsH, for TEAs pyrolysis in D 2. However, DEAsH pyrolysis produced TEAs, and MEAsH 2 decomposed to yield DEAsH and arsine, in both ambients. This suggests that a β-elimination reaction is not a major step for any of the ethylarsine precursors. More likely, radical reactions occur. When trimethylgallium (TMGa) was added, the ethylarsine pyrolysis rates were accelerated due to the CH 3 radicals produced from TMGa pyrolysis. In addition, heterogeneous reactions have been observed for pyrolysis of ethylarsines, especially when a GaAs surface was involved.

MOMBE (metalorganic molecular beam epitaxy) growth of InGaAlAsSb system on GaSb

Abstract MOMBE (metalorganic molecular beam epitaxy) growth characteristics of materials in the InGaAlAsSb system on GaSb substrates are described. The studies on GaSb growth using TEGa (triethylgallium) and solid Sb sources show that the surface reconstructions and the excess Sb on the surface play important roles in the MOMBE growth process. This is explained by a model which includes group V chemistry. The use of TESb (triethylstibine) instead of solid Sb indicates that the alkyl species coming from thermally cracked TESb also play important roles. Crystalline AlSb films are obtained using TIBAl (triisobutylaluminium), while not when using TMAl (trimethylaluminium), which is related to the difference in the reaction process. In the growth of InAsSb using TMIn (trimethylindium), TEAs (triethylarsine) and TESb, mirror-like surfaces are obtained only in the narrow TEAs/TMIn flux ratio region close to the (2×4)-(4×2) surface reconstruction transition boundary in InAs growth, and it is found that the composition of InAsSb alloy films can be controlled precisely using TMIn, TEAs and TESb. The growth characteristics of InAs and InSb are also discussed. Finally, preliminary results on the electrical and optical properties of the layers are shown to be encouraging.

The epitaxial growth of gallium arsenide using triethylarsine

AbstractThe thermal decomposition of triethylarsine (TEAs) has been studied. It decomposes at a lower temperature than arsine (AsH3). The decomposition proceeds via a radical process at a temperature above 700°C. Epitaxial growth using TEAs has been investigated. A gallium arsenide (GaAs) layer with good morphology was obtained, but the layer was found to contain a considerable amount of carbon impurity originating from TEAs. The use of TEAs with 10% AsH3 or with 20% ammonia (NH3) apparently improves the quality of GaAs layer. A possible scheme for reducing carbon incorporation is discussed.

Low-temperature GaAs epitaxial growth using electron-cyclotron resonance/metalorganic-molecular-beam epitaxy

A low-temperature GaAs epitaxial growth method called electron-cyclotron resonance molecular-beam epitaxy was newly developed. Triethylgallium (TEGa) and triethylarsine (TEAs) were used as source gases and were introduced without thermal decomposition. The method has the advantage of cleaning the GaAs substrate at the growth temperature just prior to growth as well as to decompose metalorganics with the hydrogen plasma activated by the cyclotron resonance. The epitaxial GaAs film was successfully grown at a temperature as low as 300 °C. All samples grown at 400 °C exhibited p-type conductivity for (arsine/gallium) ratios between 4 and 13. The p-type carrier concentration was strongly dependent on the (arsine/gallium) ratio and was in the range of 1016 –1019 cm−3 .

Radical block polymerization of vinyl chloride. I. Ozonized polypropylene oligomers as heterofunctional initiator

AbstractIsotactic polyproplyene has been peroxidized in the solid state by treatment with ozone at room temperature, eventually followed by treatment with oxygen at 100°C. The total active oxygen content—peroxides and hydroperoxides—was determined iodometrically, and the hydroperoxide content with triethyl arsine, following the method of Horner and Jürgens. Post‐treatment with oxygen causes a very strong increase in total active oxygen content; the relative amount of hydroperoxides compared with that without oxygen treatment is, however, markedly decreased. The stability and rate of decomposition of PPO2 have been considered in relation to the solubility parameter of the different monomers and solvents. It was used at 30–40°C for initiating the emulsion polymerization of styrene, methyl‐, and butyl methacrylate and methyl, ethyl, n‐butyl, and 2‐ethyl‐hexyl acrylate. These polymers contain an average number of peroxide links per macromolecule, ranging between 7 and 23; they can be used for the block polymerization of a second vinyl monomer, e.g., vinyl chloride.