InP Channel HEMT Development for MM-Wave Power Applications

Millimeter-wave system designers are limited to two terminal devices when high powers are required from a solid state device. InGaAs/InAlAs HEMTs latticed matched to InP substrates have produced excellent low noise results at millimeter-wave frequencies. The high power performance, however, is limited by the narrow bandgap of the InGaAs chamel which leads to low breakdown voltages between the drain and source. This proposed program will incorporate the wider bandgap InP material in the channel region to increase the device's breakdown voltage. The highest performance HEMT devices have been fabricated on epitaxial material grown by solid source molecular beam epitaxy (MBE). Phosphorous containing compounds have traditionally been difficult to handle in a solid source MBE system. The development of a valved group V cracking source has reduced many of the complications associated with using solid phosphorous. This will be the approach taken for this proposed program. The epitaxial profile will be simulated using POSES, a program developed by Gateway Modeling which solves Poisson's and Schroedinger's equations to generate device DC operating characteristics. Once the design has been optimized, wafers will be provided to a foudry for device fabrication and test to verify the improvement anticipated through the use of an InP chamel. Anticipated Benefits/Potential Applications - The material developed under this proposed program will be used for high power mm-wave HEMTs which will provide the system designer with an attractive alternative to two terminal devices.The system applications include secure communications at 60 GHz., cellular phone cell-to-cell commication at 35 GHz., and collision avoidance radar for automotive applications at 77 GHz.