InAlAs/InGaAs high electron mobility transistors(HEMTs) on an InP substrate with well-balanced cutoff frequency fTand maximum oscillation frequency fmax are reported. An InAlAs/InGaAs HEMT with 100-nm gate length and gate width of 2 × 50 μm shows excellent DC characteristics, including full channel current of 724 mA/mm, extrinsic maximum transconductance gm.max of 1051 mS/mm, and drain–gate breakdown voltage BVDG of 5.92 V. In addition, this device exhibits fT= 249 GHz and fmax = 415 GHz. These results were obtained by fabricating an asymmetrically recessed gate and minimizing the parasitic resistances. The specific Ohmic contact resistance was reduced to 0.031 Ω·mm. Moreover,the fTobtained in this work is the highest ever reported in 100-nm gate length InAlAs/InGaAs InP-based HEMTs. The outstanding gm.max, fT, fmax, and good BVDG make the device suitable for applications in low noise amplifiers, power amplifiers, and high speed circuits.
We fabricated 88 nm gate-length InP-based InAlAs/InGaAs high electron mobility transistors(HEMTs) with a current gain cutoff frequency of 100 GHz and a maximum oscillation frequency of 185 GHz.The characteristics of HEMTs with side-etched region lengths(L_(Side)) of 300,412 and 1070 nm were analyzed.With the increase in L_(Side),the kink effect became notable in the DC characteristics,which resulted from the surface state and the effect of impact ionization.The kink effect was qualitatively explained through energy band diagrams,and then eased off by reducing the L_(Side).Meanwhile,the L_(Side) dependence of the radio frequency characteristics,which were influenced by the parasitic capacitance,as well as the parasitic resistance of the source and drain,was studied.This work will be of great importance in fabricating high-performance InP HEMTs.
A physical model for scaling and optimizing InGaAs/InP double heterojunction bipolar transistors(DHBTs) based on hydrodynamic simulation is developed.The model is based on the hydrodynamic equation,which can accurately describe non-equilibrium conditions such as quasi-ballistic transport in the thin base and the velocity overshoot effect in the depleted collector.In addition,the model accounts for several physical effects such as bandgap narrowing,variable effective mass,and doping-dependent mobility at high fields.Good agreement between the measured and simulated values of cutoff frequency,f t,and maximum oscillation frequency,f max,are achieved for lateral and vertical device scalings.It is shown that the model in this paper is appropriate for downscaling and designing InGaAs/InP DHBTs.
A two-stage MMIC power amplifier has been realized by use of a l-μm InP double heterojunction bipolar transistor(DHBT).The cascode structure,low-loss matching networks,and low-parasite cell units enhance the power gain.The optimum load impedance is determined from load-pull simulation.A coplanar waveguide transmission line is adopted for its ease of fabrication.The chip size is 1.5×1.7 mm^2 with the emitter area of 16×1μm×15μm in the output stage.Measurements show that small signal gain is more than 20 dB over 75.5-84.5 GHz and the saturated power is 16.9 dBm @ 79 GHz with gain of 15.2 dB.The high power gain makes it very suitable for medium power amplification.
