SILICON SUBSTRATE OPTIMIZATION FOR MICROWAVE APPLICATIONS OF GAAS SI MESFETS/

Silicon substrates were cut at tilt angles ranging from 0 to 9 degrees off the (100) plane, and heteroepitaxial GaAs layers were grown by mo lecular beam epitaxy (MBE). The d.c. and RF performance of MESFET devi ces defined on these layers was used as a measure of the optimum subst rate tilt angle. Best performance was observed between 3 and 4.5 degre es tilt. MESFET device performance was also compared as silicon substr ate resistivity was varied from 10(-3) to 10(3) Omega cm. A minimum re sistivity of 10 Omega cm is found to be necessary for high performance heteroepitaxial MESFET devices. No effect of substrate conductivity t ype on device performance was observed. (C) 1997 Elsevier Science S.A.