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

This letter reports a novel InGaP/InGaAs/GaAs double delta-doped pseudomorphic high-electron mobility transistor (pHEMT) with n(+)-GaAs/p(+)-InGaP/n-InGaP camel-like gate structure grown by MOCVD. Due to the p-n depletion from the p(+)-InGaP gate to the channel region and the presence of DeltaEc at InGaP/InGaAs heterostructure, the turn-on voltage of gate is larger than 1.7 V. For a 1 x 100-mum(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(m) is obtained. Furthermore, the unit current cut-off frequency f(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.