MOCVD GaAs-Ga1-xAlxAs epitaxial structures to fabricate MESFET's have been successfully grown in a low pressure MOCVD system. The growth parameters were optimized to obtain very high uniform epitaxial layers (o - 2%). MESFET's were fabricated and the devices with heterobuffer layer showed good transconductance and linearity as compared to conventional GaAs buffered structures. A 7.7 dB gain was performed at Idss/2 at 18 GHz. However the breakdown voltage has to be improved by lowering the background doping in the Ga1-xAlxAs buffer layer
