Impact of materials and structures on high power gallium nitride vacuum microelectronics.

摘要

The overall motivation for this project is to determine whether field emission vacuum devices can be used to fabricate a 10 GHz amplifier capable of delivering an output power of 100W with a power added efficiency (PAE) of 75% in order to increase the power and efficiency for X-band Phased Array Radar Transmit/Receive (T/R) modules. The field-emission based 100 W device would need to have a current density of 16 muA/mum in order to achieve the goal. A combination of solid state and vacuum tube technologies potentially provide the ideal characteristics needed for this device. Therefore, a wide band-gap electron emitter was studied for the purpose of creating a vacuum microelectronic based amplifier. Gallium Nitride (GaN), Aluminum Gallium Nitride (AlGaN), and High Electron Mobility Transistors (HEMT) were processed and tested as emitter devices. The focus of this work was to study new field emitter tip geometries fabricated using a focused ion beam (FIB) to improve field enhancement. The devices were electrically tested as diodes and triodes. Lower turn-on voltages and higher current densities were achieved via field enhancement manipulation. This work was done in conjunction with Stellar Micro Devices in Austin, Texas as part of an Air Force STTR Phase II program.