Superlattices, multiple quantum wells, and other heterostructures of various semiconductors will play an increasingly important role in advanced electronics. Further development work is needed on the growth techniques used to fabricate these structures. Advanced electronic systems will require higher performance devices that will require high-quality heterostructures for radar and communications systems. At present, the two most commonly employed techniques for the growth of multilayer materials for today's complex device structures are molecular beam epitaxy (MBE) and organometallic vapor phase epitaxy (OMVPE), also known as metalorganic chemical vapor deposition (MOCVD). In the last few years a hybridization of the above two techniques has occurred, resulting in a new technique known as chemical beam epitaxy (CBE). The initial results suggest this is a superior technique for the growth of material for use in advanced device structures such as InGaAs/InP heterojunction bipolar transistors (HBTs). Disadvantages exist with both MBE and OMVPE. The inability of MBE to grow good epilayers of P- containing materials such as InP and GaInAsP will severely limit this technique for next generation devices. Furthermore, with MBE grown material, oval defects place an upper limit on the number of devices at an integrated circuit level and the overall device yield. In addition, an upper bound on doping levels translates to higher series resistance and a compromise in HBT design. Low wafer throughput and the down-time needed to reload source materials substantially increase cost and result in unpredictable time delays. The most serious problem facing the OMVPE technique is the need for high flow rates of hazardous and life-threatening gases such as arsine and phosphine. This point cannot be overemphasized: the impact on future growth techniques will be highly influenced by environmental concerns, health risks, and legal prohibition. Engineered properly CBE can overcome these problematic limitations. This proposal discusses an investigation of chemical beam epitaxy, including work on the development of new sources and the growth mechanisms. The primary focus of this investigation is to develop safe organometallic group III and group V sources that result in materials with properties superior to those produced to date by CBE and comparable to the best produced by MBE and OMVPE. The overall objective is to make significant and substantial improvements in the CBE process for the production of As-andP-based semiconductors with the major emphasis being on P-containing binary, ternary and quaternary III/V compound materials for device applications using safer, less toxic sources.
