Alternate sources and growth chemistry for OMVPE and CBE processes

Abstract

Until recently, the choice of group V source molecules for organometallic vapor phase epitaxy (OMVPE) of III/V semiconductors has been simple: only A sH 3 and PH 3 produced device quality material. The hazard posed by the hydride sources, as well as the desire for precursor molecules producing higher quality epitaxial layers has motivated the development of new, organometallic group V precursor molecules. Novel group III precursors are also under development. Fundamental knowledge of bond strengths between metal atoms and various radicals, as well as the reactivity of the radicals, has guided the development of these new source materials. In addition, some knowledge of the actual chemical reactions which constitute the growth process is also necessary for the intelligent design of new precursor molecules. This paper reviews the pyrolysis and growth reactions occuring during atmospheric pressure OMVPE growth of several III/V semiconductors. The group III precursors are discussed briefly, with the major attention paid to the group V source molecules. The pyrolysis and growth mechanisms are analyzed in an effort to predict pyrolysis and growth reactions under the ultra-high vacuum conditions of chemical beam epitaxial growth. Suggestions are made of the most promising precursors for use in this growth technique.