9313936 Feng The objective of Fundamental Speed Limitation of Ga1-xINxAS Metal- Semiconductor Field Effect Transistors (MESFETs) and High Electron Mobility Transistors (HEMTs) program is to fabricate 0.05 um gate length GaAs MESFETs and HEMTs, and to perform speed characterization of these devices over the microwave frequency band (DC-40GHz) and over a temperature range (300K to 30K). This measured information allows us to determine the high field electron velocity as a function of electrical field and to develop a simple model to predict the fundamental speed limitation of 0.05 um gate length of Ga1-xINxAS MESFETs and HEMTs. This information also allows us to verify the existence of the ballistic effect in FETs. ***