High-efficiency ion-implanted lo-hi-lo GaAs IMPATT diodes

Abstract
A dc‐to‐rf conversion efficiency of 37% combined with an output power of 3.4 W at 3.3 GHz has been obtained from a Schottky‐barrier GaAs IMPATT diode having a lo‐hi‐lo profile. The donor spike or clump was produced by implanting silicon into an epitaxial layer with a n‐type concentration of 1.65×1015 cm−3. Pyrolytic Si3N4 was used to encapsulate the GaAs during the postimplantation anneal. For these devices, the Si3N4 deposition procedure was found to be critical and had to be optimizied to achieve reproducible results. The devices have had very uniform electrical characteristics, and a large yield of devices with greater than 30% efficiency has been obtained. These results indicate that implantation can be used to produce lo‐hi‐lo IMPATT’s with significantly higher device yields than have been obtained by epitaxial techniques.