HIGH-POWER GaAs IMPATT DIODES.

This paper describes the design criteria, the fabrication techniques and the high frequency characteristics of conventional-type (M-n-n**(** plus ** plus **)) and high-low-type (M-n**(** plus **)-n-n**(** plus ** plus **)) GaAs IMPATT diodes. Conventional-type diodes which have a flat doping profile are designed on the basis of the ″Read condition″ . High-low-type diodes which have an additional active n**(** plus **) layer are designed on the basis of new design criteria. For the reduction of the thermal resistance which is most important in the fabrication process of GaAs IMPATTs, a diamond heat sink was used and optimum conditions of thermal compression bonding were experimentally examined. The thermal resistance of diodes bonded under these conditions was reduced by a factor of 25% compared to the Plated-Heat-Sink (P. H. S. ) method. The before-punch-through (B. P. T. ) diodes which have undepleted materials in the active region were hard to burn out by detuning. The detuning burnout in conventional-type diodes has been confirmed to be caused by crystal defects at the substrate-epitaxial layer interface. Conventional-type diodes fabricated with these techniques produced output powers of 4. 0 watts at 6. 0 GHz with 11. 6% efficiency. High-low-type diodes produced output powers of 10. 5 watts at 6. 7 GHz with 27. 9% efficiency.