Stable, reliable contacts to W-band Gunn diodes

Elevated temperatures maintained for long periods during operation, especially in the presence of an electric field due to applied bias, have been found to degrade performance and result in device failure. The failures are attributed to contact constituents migrating into the active region of the Gunn diode. Contact systems involving Au, Ge, Ni, Pt, W, and Ti were investigated for both anode and cathode metallizations. Results showed that both ohmic and current limiting contacts require a stable barrier metallization to separate the contact touching the semiconductor from any overlying metallizations or Au-plated regions. Au migration was identified as a major cause of device failure. A rapidly annealed Pt/Ti barrier metallization was utilized in the fabrication process. This combination showed excellent stability during accelerated temperature testing.<>