Design and technology of millimeter-wave indium aluminum arsenide/indium gallium arsenide high electron mobility transistors (HEMT's) and monolithic integrated circuits.

Abstract

Monolithic Microwave Integrated Circuits (MMIC's) are important for microwave systems. This thesis presents the optimization of InAlAs/InGaAs HEMT's for high-frequency operation, the development of modeling methods, and their application to the demonstration of InP-based MMIC's at millimeter-wave frequencies. Various possibilities have been investigated as a means to improve cut-off frequencies of the devices. The impact of gate recess and device geometry was studied and a novel offset $\Gamma$-gate self-aligned gate technology was developed. A double heterojunction (DH) design with a pseudomorphic channel was employed to achieve high current density together with high cut-off frequencies. Sub-0.1 $\mu$m offset self-aligned DH-HEMT's showed f$\sb{max}$ = 350GHz with I$\sb{d{,}max}$ = 1.2A/mm. Novel quasi-1D HEMT's were also realized with shallow gratings to improve carrier confinement. In addition, the intrinsic delay of submicron InAlAs/InGaAs HEMT's has been studied theoretically. An accurate HEMT modeling method was developed based on an equivalent circuit parameter extraction technique and a large-signal analysis method using the 2-D interpolation and harmonic balance method. The HEMT model was validated with measured S-parameters and load-pull results. The large-signal analysis method has been extended to frequency-domain analyses of oscillators and mixers. Three different types of nonlinear monolithic circuits have been realized at mm-wave frequencies using InAlAs/InGaAs HEMT's. Monolithic mixers have been demonstrated at W-band using HEMT's and diodes. A monolithic single-gate mixer demonstrated $\sim$1 dB of conversion gain at 94 GHz, and a miniaturized mixer using dual-gate HEMT's has been realized with a small chip size of 1 $mm\sp2$. Oscillators have been realized from 35 GHz to 130 GHz. Ka-band monolithic oscillators showed a record DC-to-RF efficiency of 36% and W-band oscillators showed an output power of 1.2 mW at 77 GHz. A fundamental HEMT oscillator has for the first time been demonstrated at 130 GHz with an output power of $-$7.9 dBm. The use of HEMT's for frequency upconversion has been studied and 90-to-180 GHz monolithic HEMT doublers have been realized with a conversion loss of 6 dB. A fully integrated oscillator-doubler chain has also been demonstrated at 132 GHz.