STUDY OF SURFACE REACTION IN MOCVD AND ALE USING IN AND P COMPOUNDS

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InP is a potential material for application to high speed and optical devices. Thin films of InP is usually fabricated by molecular beam epitaxy (MBE), metalorganic chemical vapor deposition (MOCVD), etc. From practical point of view, MOCVD is a useful method for fabrication of the film. Since the film is formed by surface chemical reaction of complex metalorganic compounds on semiconductor substrates, the reaction should be controlled to obtain good quality samples. Therefore, it is necessary to elucidate the reaction mechanism for the fabrication.The first step of the reaction is adsorption and subsequently decomposition and reaction occur on substrate surfaces, forming the films in MOCVD.Therefore, it is very important to study absorption and decomposition of the metalorganic compounds on the surfaces. Interface between the film and the substrates, which is controlled by the first absorption and following decomposition of the compounds, strongly affects electrical properties of devi … More ces.We have studied absorption and decomposition of triethylindium (TEI), trimethylphosphine (MP), triethylphosphine (TEP), and tertiarybutylphosphine (TBP), which have been used as precursors for MOCVD and ALE,on the Si (111)-7x7, Si (001), and GaP (001) surfaces using AES,PXS,UPS,STM,TPD,HREELS, RHEED.We obtain the following results.1. TMP absorbs preferably on centered adatom sites on a Si (111)-7x7 surface.2. TEI and TEP absorb molecularly on the Si (001) and GaP (001) surfaces at RT and are decomposed into ethylene and hydrogen, leaving In and P atoms on the surfaces, respectively.3. TBP is partially dissociated on the Si (001) and GaP (001) surfaces at RT and is decomposed into isobutylene and hydrogen, leaving P atoms on the surfaces.4. TEI,TEP,and TBP are decomposed through beta-hydride elimination.5. Decomposition reaction of TEI,TEP,and TBP on the GaP (001) surface are strongly affected with hydrogen ambience but not on the Si (001) surface, which is due to the fact that dissociative absorption of hydrogen occurs on GaP (001) but does not on Si (001).6. The decomposition mechanisms of TEI,TEP,and TBP on the Si (001) and GaP (001) surfaces were proposed. Less