The growth of high performance In/sub x/Ga/sub 1-x/As(0.52

InP-based HEMT devices have long surpassed GaAs-based devices for high frequency, low noise amplification applications. Future improvements in device and circuit performance will result from enhanced electron transport properties, as well as epitaxial layer designs which allow for improved device scaling. In this paper, we report the successful attempts at significantly improving the electron mobility in thin channel, device structures with high two-dimensional electron gas (2DEG) concentrations. We believe that we have achieved the highest room temperature electron mobility to date for this materials system in structures with both high and low 2DEG concentrations.<>