THE MOLECULAR-BEAM EPITAXIAL-GROWTH OF GAAS ON SI(100) - A VARIABLE GROWTH TEMPERATURE STUDY

Epitaxial GaAs layers, with a thickness of 4.1-mu-m, have been grown on Si(100) substrates using a two-step process involving a thin, low temperature, slow growth rate, buffer layer followed by an active (i.e. doped) layer. The active layers were grown at various temperatures in the range 330 less-than-or-equal-to T(G) less-than-or-equal-to 620-degrees-C. Two methods were employed for the growth of the buffer layer. In the first instance the buffer was annealed at the growth temperature of the subsequent active layer; the electrical and structural properties of these epilayers were observed to improve with increasing growth temperature. In the second case the buffer layers were all annealed at 615-degrees-C prior to the growth of the active layer. For these samples the variation in the electrical properties with the growth temperature resembled those obtained for homoepitaxial GaAs(100); whereas the structural quality again improved with increasing deposition temperature. This study, therefor, emphasizes the importance of the quality of the buffer layer in the two-step process, and shows that both the structural and electrical properties of the heteroepitaxial GaAs epilayers may be improved by incorporating an annealing cycle into the growth process.