Electrical properties of single delta-doped InGaP/InGaAs/GaAs pseudomorphic HEMT with camel-like gate structure

The paper presents the electrical properties of a newly designed single delta-doped InGaP/InGaAs/GaAs pseudomorphic high electron mobility transistor (HEMT) with n+-GaAs/p+-InGaP/n-InGaP camel-like gate structure. For a 1×100 μm2 device, the experimental results exhibit an extrinsic transconductance of 85 mS mm−1 and a saturation current density of 425 mA mm−1. Significantly, due to the p–n depletion from p+-InGaP gate to channel region and the presence of considerable conduction band discontinuity at InGaP/InGaAs heterostructure, the gate-to-drain turn-on voltage is larger than 1.7 V. In addition, an extremely broad gate voltage swing larger than 3 V with above 80% maximum gm is obtained. The unit current cutoff frequency fT and maximum oscillation frequency fmax are up to 18 and 30 GHz, respectively.