Improved fabrication and noise performance of silicon double-drift millimeter-wave IMPATT diodes

Silicon double-drift IMPATT diodes with both drift regions implanted into π (undoped) epi on p⁺substrates are discussed. By incorporating doubly-charged ions, frequency coverage, has been extended down to 40 GHz. The π epitaxial material was characterized by spreading resistance measurements so that the ions were implanted into a completely defined host material lattice. RF test results at 55 GHz comparing single-and double-drift diodes are given. Noise figure measurements show that the transition from small- to large-signal behavior begins at a power output ∼ 3 dB greater with double-drift diodes. At reasonable outputs this results in ∼ 10 dB noise improvement (1).