Some comparisons of chemical beam epitaxy with gas source molecular beam epitaxy

Abstract This paper seeks to illustrate the major differences between chemical beam epitaxy (CBE) and gas source molecular beam epitaxy (GSMBE). The reasons for these differences nearly all eminate from the use of group III metal alkyls in CBE whereas GSMBE uses conventional elemental group III sources. From this difference can be traced the dissimilarity in growth mechanisms which can be further exemplified in some of the more important features of CBE. Using as an illustration the growth of GaAs from triethyl gallium, the model is extended to include the reduction in growth rate brought about by the addition of small quantities of In to the growing layer at temperatures in excess of 500°C. This is technologically important in the subsequent growth of InGaAs lattice matched to InP. The positive advantages of CBE, such as area uniformity and true selective area growth are also discussed in detail. InGaAs layers have been grown with a compositional uniformity of ±0.03% In and a thickness variation of