Characterization of Enhancement-Depletion Mode AlInN/GaN HEMTs Using Partial p-type GaN Gate

This work attempts to characterize the novel Enhancement mode (E-mode) AlInN/GaN HEMT devices implemented using p-GaN gate for getting positive threshold voltage (V-t). The device uses lattice-matched Al0.83In0.17N and GaN composite semiconductor layers in channel, with p-GaN layer below the E-mode device. The comparison of E-mode and Depletion mode (D-mode) devices is comprehensively done. The hydrodynamic model of Sentaurus TCAD is used to perform 2D simulations. The simulation setup and model is calibrated by comparing the simulated results with experimental result from published papers. A complete, quantifiable examination of transfer characteristics, transconductance, gate capacitance, gate leakage and RF gain for D-mode and E-mode devices is done. The E-mode and D-mode devices exhibit a V-t of + 1.0 V and -3.7 V respectively. Both devices exhibit almost similar transconductance characteristics. The E-mode device shows lower off-state leakage current, higher I-ON/I-OFF ratio and lower subthreshold slope (SS) than D-mode device. The E-mode device exhibits slightly enhanced RF characteristics as compared to D-mode device. These results demonstrate the feasibility for fabricating an E-mode AlInN/GaN HEMT device which is needed in application demanding high speed and high frequency operation.