Double-drift ion implanted (P+PNN+) millimeter wave IMPATT diodes

Double-drift-space IMPATT diodes made of ion implantation have been shown to offer advantages over conventional IMPATT structures. Recent advances in fabrication techniques have led to improved performance for the new structure, and in this paper comparative results are reported for single- and double-drift-space diodes designed for 50-GHz CW oscillator operation. The maxim am output power obtained from a double-drift is 1 watt, compared to 0.53 watt for single-drift doides. A maximum efficiency of 14.2% (at 0.93 watt) is obtained for the double-drift diode and 10.4% (at 0.46) watt) for the single-drift diode. The power-frequency-squared figure of merit for the double-drift device is the highest obtained for any CW IMPATT diode in any frequency range. All measurement techniques and process steps were the same for both types of units. The only significant difference is in the structure of the device: p⁺-p-n-n⁺compared with p⁺-n-n⁺. Ion implantation was used to make the p region of the 50- GHz double-drift structure. Static characteristic measurements are compared with calculations to determine the doping and to indicate the desired doping for frequencies up to 110 GHz. Preliminary experimental results for 100-GHz operation have been obtained for double-drift structures with both p and n regions implanted and will be given.