Metamorphic HEMT technology for millimeter-wave and 40-Gb/s fiber-optics applications

We have developed a 0.15-μm T-gate metamorphic HEMT process with three-level metal interconnects on 100-mm GaAs substrates for low noise and fiber-optics applications. Hall mobilities of greater than 10,000 cm²/Vsec and sheet charge densities of 3.6 × 10¹² cm^-2 at room temperature were routinely achieved for MHEMT epitaxial layers. Very low noise figure of 0.3 dB and high associated gain of 14.5 dB were measured at 10 GHz. Three 40-Gb/s fiber-optics circuits and a 77 GHz oscillator were successfully demonstrated using this single-recess MHEMT on GaAs technology. OC768 transimpedance amplifiers (TIAs) with differential output exhibited state-of-the-art performance of greater than 55 dBΩ transimpedance.