CHEMICAL SURFACE MECHANISTIC CONSIDERATIONS IN THE DESIGN OF NOVEL PRECURSORS FOR METALORGANIC MOLECULAR-BEAM EPITAXY

in the design of chemical precursors for metalorganic molecular beam epitaxy (MOMBE), the following issues must be considered: the intrinsic decomposition pathways of the source, the interaction of the reactant and products with the interface, and volatility and safety of the precursor. A representative example would be the development of alternative group V metalorganic sources as arsine and phosphine substitutes. The standard sources used in MOMBE in growing GaAs or any other arsenic based III-V material are typically solid arsenic or thermally cracked arsine. Both sources produce As2 and/or As4 which then are transported to the growth surface. Although these are used effectively in III-V growth, chemical substitutes are desirable for a number of reasons, including safety, minimization of system corrosion, and selectivity. A number of alternative arsine substitutes have been suggested over the years, but this paper will focus mainly on the mechanistic design considerations of three group V materials; tertiary butyl arsine (TBAs), phenyl arsine (PhAs), and tris-dimethylamino arsenic (DMAAs). Other examples of group III chemical precursors for MOMBE will also be considered.