High performance InP/InGaAs/InP DHBTs with patterned sub-collector fabricated by elevated temperature N+ implant

We have demonstrated InP/InGaAs/InP MBE-grown DHBTs fabricated with patterned sub-collector by elevated temperature 200 °C N+ implant and subsequent device material over growth. Ft/Fmax > 250 GHz/300 GHz were obtained on DHBTs with 0.35 μm × 6 μm emitters from this process. Ring oscillators fabricated with this process showed good uniformity with 82% of yield on wafers and an average gate delay of 8 ps. Difference of surface morphology on re-grown DHBT layers over elevated temperature implanted and room temperature 22 °C implanted sub-collector was observed.