InAlAs/InGaAs Metamorphic High Electron Mobility Transistors on GaAs Substrate: Influence of Indium Content on Material Properties and Device Performance (original) (raw)
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InAlAs/InGaAs Metamorphic High Electron Mobility Transistor with Cu/Pt/Ti Gate and Cu Airbridges
Japanese Journal of Applied Physics, 2007
The use of a Cu/Pt/Ti Schottky contact structure and Cu-based airbridges for high-frequency metamorphic high electron mobility transistor (MHEMT) is successfully developed. The material characteristics of the Cu/Pt/Ti Schottky contact on i-InAlAs were studied. Judging from the results of the X-ray diffraction analysis, Auger electron spectroscopy, and transmission electron microscopy, the Cu/Pt/Ti Schottky contact structure on InAlAs was very stable after annealing at 350 C. However, after 400 C annealing, the reaction of copper with the layers underneath started to occur and formed the Cu 4 Ti phase. The Cumetallized MHEMT using the proposed Cu/Pt/Ti T-gate structure and Cu-based airbridges has a saturated drain current of 673 mA/mm and a maximum transconductance of 750 mS/mm. The gate to drain breakdown voltage measured was 14.5 V at a gate reverse current of À1 mA/mm. The device also demonstrated a cutoff frequency F t of 90 GHz and a maximum frequency of oscillation F max of 165 GHz. An MHEMT with a Au/Pt/Ti gate was fabricated and compared with an MHEMT fabricated with the proposed Cu/Pt/Ti gate. These two kinds of MHEMTs showed similar F t and F max. These results demonstrate that the Cu/Pt/Ti T-gate and Cu-based airbridges can be used for MHEMT fabrication with excellent electrical characteristics.
Microelectronics Reliability, 2015
In this work, the InAs/AlSb high electron mobility transistors (HEMTs) on GaAs semi-insulating substrate using refractory iridium (Ir) gate technology was proposed. The Ir-gate exhibited a superior metal work function which was beneficial for increasing Schottky barrier height of InAs/AlSb heterostructures to 0.58 eV. Compared to the Ti-gate HEMT, the Ir-gate HEMT shows higher threshold voltage and lower gate leakage current owing to its higher Schottky barrier height and higher melting point. Moreover, the Irgated HEMT also shows the manifest stability improvement of DC characteristics under hot carrier stress as the Ti and As diffusion is alleviated.
IEEE ELECTRON DEVICE LETTERS, 2010
High-performance metamorphic high-electron mobility transistors (MHEMTs) using an (InxGa1−xAs)m/(InAs)n superlattice structure as a channel layer have been fabricated successfully. These HEMTs with 80-nm gate length exhibited a high drain current density of 392 mA/mm and a transconductance of 991 mS/mm at 1.2-V drain bias. Compared with a regular InxGa1−xAs channel, the superlattice-channel HEMTs showed an outstanding performance due to the high electron mobility and better carrier confinement in the (InxGa1−xAs)m/(InAs)n channel layer. When biased at 1.2 V, the current gain cutoff frequency (fT ) and the maximum oscillation frequency (fmax) were extracted to be 304 and 162 GHz, respectively. As for noise performance, the device demonstrated a 0.75-dB minimum noise figure (NFmin) with an associated gain of 9.6 dB at 16 GHz. Such superior performance has made the devices with a superlattice channel well suitable for millimeter-wave applications.
IEEE Transactions on Electron Devices, 1999
A simple model to describe the dependence of the breakdown voltage between gate and drain on width of the gate recess in an InAlAs/InGaAs high electron mobility transistor (HEMT) is presented. In this model, the depletion region laterally spreads to the drain region. It enables us to express the dependence of device parameters on the width of the gate recess. The model suggests that the breakdown voltage increases with the width of the gate recess and then saturates, which is experimentally confirmed. Calculations based on the model show that the maximum frequency of oscillation (f f f max ) also increases with the width of the gate-recess due to the reduction in both the drain conductance and the gate-to-drain capacitance, and then slightly decreases with the width due to the increase in the source resistance. We fabricated InAlAs/InGaAs HEMT's lattice-mismatched on GaAs substrates with optimum recess-width, and these exhibited both a high breakdown voltage of 14 V and a high f f f max of 127 GHz at a gate length of 0.66 m. I. INTRODUCTION I nAlAs/InGaAs HEMT's (high electron mobility transistors)
IEEE Electron Device Letters, 2000
A novel InGaAs/InAlAs insulated gate pseudomorphic HEMT (IG-PHEMT) utilizing a silicon interface control layer (Si ICL) was successfully fabricated and its DC and RF performances were characterized. The device showed high transconductance of 177 mS/mm even for a gate length of 1.6 m. As compared with the conventional Schottky gate PHEMTs, the gate leakage current was reduced by 4 orders of magnitudes and the gate breakdown voltage was increased up to 39 V. Well-behaved RF characteristics with the current gain cutoff frequency, T , of 9 GHz and the maximum oscillation frequency, max , of 38 GHz were obtained for the 1.6 m-gate-length device.
IEEE Transactions on Electron Devices, 2000
We have fabricated and characterized ultrashort gate-length metamorphic high-electron mobility transistors (HEMTs) optimized for high gain performance for millimeterand submillimeter-wave applications. In this paper, we have systematically evaluated the impact of gate length in the range of 25-50 nm on the device performance by exploring epitaxial layer designs, gate-to-channel distances, and recess widths. The study shows the 25-nm devices underperform their 50-nm counterparts in most of the key figures of merit including output conductance, voltage gain, off-state breakdown, on-state breakdown, and, most importantly, the maximum stable gain. This observation is actually in good agreement with the state-of-the-art results published so far, which indicate that the best overall performance of HEMTs for millimeter-and submillimeter-wave applications comes from devices with gate lengths ranging from 35 to 50 nm. The 25-nm devices, on the other hand, appear to have difficulty in achieving the proper vertical scaling for optimum gain, which is limited by the minimum gate layer thickness necessary to retain good Schottky characteristics. This limitation may eventually be overcome with the adoption of new materials used as the gate layer that can be integrated into the HEMT fabrication process.
IEEE Transactions on Electron Devices, 1998
A process for the monolithic integration of enhancement- and depletion-mode high electron mobility transistors (E/D-HEMTs) on InAlAs/InGaAs/InP is reported. The E-HEMTs with a 1.0-μm gate length exhibit a threshold voltage of +255 mV and a maximum dc extrinsic transconductance of 503 mS/mm at room temperature, while a threshold voltage of -317 mV and a transconductance of 390 mS/mm are measured for the D-HEMTs of the same gate length. The devices show excellent RF performance, with a unity current-gain cutoff frequency (ft) of 35 GHz and a maximum frequency of oscillation (fmax) of 95 GHz for both the E- and D-HEMT's. To the best of the authors' knowledge, this is the first demonstration of an E/D-HEMT technology on lattice-matched InP that is suitable for circuit integration
International Electron Devices Meeting 2000. Technical Digest. IEDM (Cat. No.00CH37138), 2000
Simulation results of InAlAs/InGaAs High Electron Mobility Transistors based on both GaAs and InP substrates are presented using the two-dimensional device simulator MINIMOS-NT. Three different HEMT technologies are evaluated by simulation and a single set of physical parameters is verified. The critical interaction of selfheating, impact ionization, SiN surface effects, and material composition is incorporated, which renders the simulation results suitable for the evaluation of device reliability issues. Starting from the analysis of gate-currents the simulation model can quantitatively support the basic understanding of this advanced material system. 0-7803-6441-4/00/$10.00 (C) 2000 IEEE