Chemical/surface mechanistic considerations in the design of novel precursors for metalorganic molecular beam epitaxy

Abstract

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 As 2 and/or As 4 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.