ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Thermal decomposition mechanisms have been inferred for a series of organoarsine chemical vapor deposition precursors, and this data has been correlated with the quality of GaAs films grown from these reagents. Tri-, di-, and mono-ethylarsine, as well as a mixture of triethylarsenic and arsine, were pyrolyzed under pseudogrowth conditions, and their decomposition mechanisms were inferred from a qualitative and quantitative analysis of the reaction mixture components. The primary decomposition step for the ethylarsines appears to be a thermally induced, arsenic-carbon bond homolysis to produce both an ethyl radical and an alkyl and/or hydride substituted arsenic radical species. For a mixture consisting of arsine and triethylarsenic, it appears that the triethylarsenic reagent undergoes arsenic-carbon bond homolysis, and the radicals thus produced enhance the decomposition of the arsine coreagent. The more highly substituted ethylarsine reagents were found to generate the greatest number of alkyl-substituted arsenic radicals upon decomposition, and also produced the least pure GaAs films. Since alkylarsenic radicals can react with a growing GaAs epilayer to cause severe carbon contamination, this decomposition data is consistent with the observed growth results. In the coreagent mixture, the free-radical activation of arsine results in a large production of dihydridoarsenic radicals, which is consistent with the high-purity, low-carbon films produced from this reagent mixture. These results indicate that any viable organoarsenic precursor must decompose preferentially to produce hydrido-arsenic radical intermediates, in order to produce high-purity GaAs epilayers.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.348554
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