EFFECT OF IONIZATION AND ACCELERATION OF AS-SOURCE BEAM ON LOW-TEMPERATURE EPITAXIAL-GROWTH OF GAAS ON EXACT (100)SI

The growth of GaAs films on on-axis (100) Si was studied using ionized source beam epitaxy (ISBE) at the growth temperatures in the range of 160-280-degrees-C. A single crystal GaAs layer could be epitaxially grown on Si at a substrate temperature as low as 160-degrees-C by using an accelerated partially ionized As-source beam. Both ionization and acceleration of the As beam enhanced two-dimensional growth of GaAs even when As-incorporation was not a rate-limiting factor. It is believed, however, that the energy required for the single crystal growth (especially at a temperature as low as 160-degrees-C) was mostly provided by the acceleration of the ionized source beam. The quality of the GaAs crystal depended on the As-to-Ga flux ratio. Both ionization and acceleration of the As-beam gave rise to an increase in the GaAs growth rate in situations where As-incorporation could be one of the rate-limiting steps in the growth of the GaAs crystal. The surface morphology, crystallinity, and microstructure of the epitaxial GaAs films grown on Si (100) were evaluated using in situ reflection high energy electron diffraction, X-ray diffraction, and cross section transmission electron microscopy.