Fort Monmouth-University of Massachusetts: Mechanistic Studies of MOCVD Growth

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The focus of our proposed research is to investigate the surface reactions occurring during the growth of III-V semiconductors by metal organic chemical vapor deposition, MOCVD. Many kinetic and mechanistic models for MOCVD have been proposed that include numerous reactions steps and kinetic parameters. However, few studies have been conducted to study the reactions occurring at the surface during the growth of III-V semiconductors. In situ techniques are available to characterize surface reactions but they are normally limited to study lower temperatures and pressures than those employed in MOCVD growth (to 1Atm.and500oC). Most notably, transmission and reflectance infrared spectroscopy in conjunction with isotopic labelling has revolutionized our understanding of catalytic reaction on solid surfaces. As temperature increases, semiconductors are no longer transparent in the infrared and transmission techniques can not be employed; indeed, these solids begin to emit radiation. Fortunately, the spectra of the emitted radiation can be analyzed by similar techniques and contains similar information with regard to the adsorbed intermediates. Thus, emission spectroscopy may be an effective tool for determining these reactive species for higher temperature reactions on semiconducting surfaces. We propose to use infrared emission spectroscopy in conjunction with isotopic tracers and on-line mass spectroscopy to investigate the surface species during the adsorption and reaction and to show how different precursors effect surface compositions. In parallel transmission infrared and detailed surface analyses for the same samples will be conducted at Fort Monmouth. This unique combination of complementary techniques will then be used to better determine surface reaction models for growth of II-V semiconductor surfaces.