A novel InGaP/InGaAs/GaAs double (delta)-doped pHEMT with camel-like gate structure

The author reports a novel InGaP/InGaAs/GaAs double delta-doped pseudomorphic highelectron mobility transistor (pHEMT) with n/sup +/-GaAs/p/sup +/-InGaP/n-InGaP camel-like gate structure grown by MOCVD. Due to the p-n depletion from the p/sup +/-InGaP gate to the channel region and the presence of (delta)Ec at the InGaP/InGaAs heterostructure, the turn-on voltage of gate is larger than 1.7 V. For a 1*100-(mu)m/sup 2/ device, the experimental results show an extrinsic transconductance of 107 mS/mm and a saturation current density of 850 mA/mm. Significantly, an extremely broad gate voltage swing larger than 6 V with above 80% maximum g/sub m/ is obtained. Furthermore, the unit current cut-off frequency f/sub T/ and maximum oscillation frequency are up to 20 and 32 GHz, respectively. The excellent device performance provides a promise for linear and large signal amplifiers and high-frequency circuit applications.