Performance of InGaP/InGaAs/GaAs camel-gate single /spl delta/-doping pHEMT

A newly designed single delta-doped InGaP/InGaAs/GaAs pseudomorphic HEMT with n/sup +/-GaAs/p/sup +/-InGaP/n-InGaP camel gate structure has been first fabricated and demonstrated. For a 1/spl times/100 /spl mu/m/sup 2/ device, the experimental results show an extrinsic transconductance of 85 mS/mm and a saturation current density of 425 mA/mm. Significantly, due to the p-n depletion from p/sup +/-InGaP gate to channel region and the presence of /spl Delta/Ec at InGaP/InGaAs heterostructure, the turn-on voltage of gate is larger than 1.7 V. In addition, an extremely broad gate voltage swing larger than 3 V with above 80% maximum g/sub m/ is obtained. The unit current cutoff frequency f/sub T/ and maximum oscillation frequency f/sub max/ are up to 18 and 30 GHz, respectively.