The objective of this Phase I effort is to design and develop a process for producing GaAs-based MESFET devices which exhibit superior thermal performance while maintain normal electrical operation. The need for advanced cooling technologies is widely recognized. Many systems are have reached a limit in integration density. This limit is imposed by the inability of current packaging technologies to remove excess heat effectively. The problems related to power dissipation are especially acute in GaAs-based systems, such as transmitters for radio frequency applications. ELO Technologies will use a combination of heterogeneous material integration and substrate removal processing to dramatically improve the thermal extraction of a GaAs-based MESFET device. Ultra-thin processing methods will allow for the placement of a metal heat pipe within a few microns of the heat source, significantly reducing the thermal impedance. A through-via electrical connection between the heat pipe and gate electrode will act to eliminate the parasitic capacitance associated with the heat pipe. The benefits of this technology include increased device density, improved circuit performance, and longer operating life.