Epitaxial Optimization of 130-nm Gate-Length InGaAs/InAlAs/InP HEMTs for High-Frequency Applications

In this paper, the influence of epitaxial-layer design on high-frequency properties of 130-nm gate-length InGaAs/ InAlAs/InP high-electron-mobility transistors (InP HEMTs) has been investigated. The In channel content ([In]: 53%, 70%, and 80%), the J-doping concentration (delta: 3, 5, and 7times1012cm-2), and the Schottky-layer thickness (dSL: 9,11, and 13 nm) have been varied. The maximum frequency of oscillation fmax, the cutoff frequency fT, the drain-to-source current JDS, and the transconductance gmhave been analyzed for InP HEMTs. All devices exhibited an increase in IDSwith increasing [In], delta, and dSL. An increase in fmax, fT, and gmwere observed with increasing [In]. When changing [In] from 53% to 80%, fTand fmaximproved by 14% and 21%, respectively. For the delta parameter, an increase in fTand gm. was found. However, fmaxwas drastically reduced for the highest delta. This is suggested to be due to the formation of a parasitic conduction channel located at the doping plane in the HEMT structure for delta > 6.3 times 1012cm-2. For the dSLparameter, an optimum with respect to fmax, fT, and gm. was observed. The optimized HEMT exhibited an extrinsic fTand fmaxof 250 and 300 GHz, respectively.