Growth of high quality GaAs layers directly on Si substrate by molecular-beam epitaxy

A study of molecular-beam epitaxy growth conditions that lead to high quality GaAs epitaxial layers grown directly on (100) Si substrates without the use of superlattice buffers is reported. An initial nucleation process which involves a predeposition of As on the Si surface and an in situ thermal annealing step immediately after the initial growth is shown to yield high quality GaAs layers with only a thin buffer layer. The effect of the growth initiation temperature is investigated and an optimal value for this temperature is found that results in smooth GaAs surface morphology. GaAs layers with relatively thin buffer layers grown under optimum conditions exhibit considerably improved electrical and optical properties, with Hall mobility and photoluminescence linewidth similar to those of homoepitaxial GaAs layers.