GaAs on Si-the ultimate wafer?

There are two basic reasons why growing GaAs on Si could be worthwhile. First, it could provide a low-cost, robust source of GaAs wafers. Growing single crystals of GaAs is relatively difficult, and GaAs wafers are generally smaller and more expensive than their silicon counterparts. They are also more fragile and prone to breakage. Secondly, it would allow high-speed digital Si, high-frequency analogue GaAs and the interchip connections to be integrated on a single substrate. The author discusses the defect densities of the GaAs layer due to lattice mismatch and then describes how the problem can be overcome by using strained layer superlattices grown by MOVPE