The indium content in metamorphic As/As HEMTs on GaAs substrate: a new structure parameter (original) (raw)
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Solid-state Electronics, 2000
State-of-the art metamorphic In x Al 1Àx As/In x Ga 1Àx As HEMTs (MM-HEMTs) on a GaAs substrate with dierent indium compositions x 0X33, 0.4 and 0.5 have been realized and characterized. The gate lengths L g are 0.1 and 0.25 lm. These devices have been compared with lattice matched HEMTs on an InP substrate. DC-characteristics of 0.1 lm gate length MM-HEMTs show drain-to-source current I ds of the order of 550±650 mA/mm, and extrinsic transconductance of about 800 mS/mm. Schottky characteristics exhibit a gate reverse breakdown voltage varying from )14 to )7 V for x 0X33±0.5, with an intermediate value of )10.5 V for x 0X4. A small signal equivalent circuit of our 0.1 lm MM-HEMTs give intrinsic transconductance higher than 1100 mS/mm, with similar values of 1350 and 1450 mS/mm for x 0X5 and the lattice matched HEMT, respectively. The MM-HEMTs with a gate length of 0.25 lm present a cuto frequency f T close to 100 GHz. To achieve the same result with pseudomorphic HEMTs on GaAs, a smaller gate length has to be realized, which requires the use of an electron beam lithography and therefore increases the device costs. For L g 0X1 lm, f T reaches 160, 195 and 180 GHz for x 0X33, 0.4 and 0.5, respectively. These values are close to f T 210 GHz obtained for a lattice matched HEMTs on InP realized with the same technological process. The MM-HEMTs are therefore good alternatives to PM-HEMTs on GaAs and LM-HEMTs on InP in the V bands and W bands while maintaining a GaAs substrate. Moreover, metamorphic In 0X4 Al 0X6 As/In 0X4 Ga 0X6 As HEMTs exhibit a comparable microwave performance with large voltage operation than the MM-HEMT with a 0.5 indium content and the lattice matched HEMTs. These results indicate that a device with indium content x 0X4 is particularly attractive for the realization of low-noise and power circuits on the same wafer. Ó
IEEE Transactions on Electron Devices, 1998
A numerical model describing the influence of InAs mole fraction on metamorphic HEMT structures (MM-HEMT) is proposed. The material properties are calculated using the Monte Carlo method, while the charge control law is calculated using a self-consistent solution of Poisson's and Schrödinger's equations. The modeling of the dc, ac, noise and high frequency performance of a device with 0.25-m gate length is performed using the quasitwo-dimensional (Q2D) approach. This analysis shows that an InAs mole fraction of about 0.40 is an optimum composition for manufacturing high gain, low noise amplifiers. In this range of composition, the performance of MM-HEMT structures is similar to that obtained for lattice-matched HEMT's on InP substrates.
IEEE Electron Device Letters, 2000
A double-pulse-doped InAlGaAs/In 0.43 Ga 0.57 As metamorphic high electron mobility transistor (MHEMT) on a GaAs substrate is demonstrated with state-of-the-art noise and power performance. This 0.15-µm T-gate MHEMT exhibits high on-and off-state breakdown ( 6 V and 13 V, respectively) which allows biasing at 5 V. The 0.6-mm device shows 27 dBm output power (850 mW/mm) at 35 GHz-the highest reported power density of any MHEMT. Additionally, a smaller gate periphery 2 × 50 µm (0.1 mm) 43% MHEMT exhibits a min = 1 18 dB and 10.7 dB associated gain at 25 GHz, and also is the first noise measurement of a ∼40% In MHEMT. A double recess process with selective etch chemistries provides for high yields.
Fabrication and characterization of In0.52Al0.48As/In0.53Ga0.47As E/D-HEMTs on InP substrates
Solid-State Electronics, 2006
The design, fabrication, and electrical characterization of enhancement-mode HEMTs (E-HEMTs) and depletion-mode HEMTs (D-HEMTs) on a common InP substrate are reported. The integration of E-and D-HEMTs (E/D-HEMTs) is a potentially useful technology for the realization of high-speed, low-power digital circuits. The layer structures for E/D-HEMTs were optimized in terms of the thicknesses of the spacer and Schottky layers and sheet carrier concentration in the channel. The buried-Pt gate technology was utilized to achieve the desired threshold voltages for both 0.15 lm gate E-and D-HEMTs. The fabricated devices exhibited threshold voltages of À0.3 and 0.1 V, peak transconductance (G m,max) values that are higher than 1020 and 1050 mS/mm, and the voltages where the peak transconductances occurred (V gp) were 0.0 and 0.4 V for D-and E-HEMTs, respectively. Unity gain cutoff frequencies (f T 's) above 190 and 180 GHz were obtained for D-HEMTs and E-HEMTs, respectively.
IEEE TRANSACTIONS ON ELECTRON DEVICES, 2010
In this paper, we report the first result of a strained In0.52Ga0.48As channel high-electronmobility transistor (HEMT) featuring highly doped In0.4Ga0.6As source/drain (S/D) regions. A lattice mismatch of 0.9% between In0.52Ga0.48As and In0.4Ga0.6As S/D has resulted in a lateral strain in the In0.52Ga0.48As channel region, where the series resistance is reduced with highly doped S/D regions. An experimentally validated device simulation is advanced for the proposed HEMT, and the results of this paper have shown that there are 60% drive-current and 100% transconductance improvements, compared with the conventional structure. A remarkable 150-GHz increase in the cutoff frequency has been seen for the proposed structure over the conventional one as well for the shown devices.
IEEE Transactions on Electron Devices, 1995
A b s h c t -In this paper we present a comparative study of the high frequency performance of 80-200 nm gate length AI0 25 GaAslGaAs/(GaAs:AlAs) superlattice buffer quantum well (QW) HEMT's, A10 3GaAsLno 15 GaAsIGaAs pseudomorphic HEMT's and In0 spAlAs/Ino.ss GaAsLnP pseudomorphic HEMT's. From an experimental determination of the delays associated with transiting both the intrinsic and parasitic regions of the devices, effective electron velocities in the intrinsic channel region under the gate of the HEMT's were extracted. This analysis showed no evidence of any systematic increase in the effective channel velocity with reducing gate length in any of the devices. The effective electron velocity in the channel of the pseudomorphic In0 65 GaAsLnP HEMT's, determined to be at least 2.5 x105 ms-l, was around twice that of either the A10 25GaAsIGaAs quantum well or pseudomorphic In0 15GaAs/GaAs HEMT's, resulting in 80 nm gate length devices with f~' s of up to 275 GHz. We also show that device output conductance is strongly material dependent. A comparison of the different buffer layers showed that the (GaAs:AlAs) superlattice buffer was most effective in confining electrons to the channel of the AI0 25GaAdGaAs HEMT's, even for 80 nm gate length devices. We propose this may be partly due to the presence of minigaps in the superlattice which provide a barrier to electrons with energies of up to 0.6 eV. The output conductance of pseudomorphic Ino 65GaAsLnP HEMT's was found to be inferior to the GaAs based devices as carriers in the channel have greater energy due to their higher effective velocity and so are more difficult to confine to the 2DEG. and Technology of China, and the M.S.E. and Ph.D.
Millimeter-wave low-noise and high-power metamorphic HEMT amplifiers and devices on GaAs substrates
IEEE Journal of Solid-State Circuits, 2000
This paper reports on state-of-the-art HEMT devices and circuit results utilizing 32% and 60% indium content InGaAs channel metamorphic technology on GaAs substrates. The 60% In metamorphic HEMT (MHEMT) has achieved an excellent 0.61-dB minimum noise figure with 11.8 dB of associated gain at 26 GHz. Using this MHEMT technology, two and three-stage Ka-band lownoise amplifiers (LNAs) have demonstrated 1.4-dB noise figure with 16 dB of gain and 1.7 with 26 dB of gain, respectively. The 32% In MHEMT device has overcome the 3.5-V drain bias limitation of other MHEMT power devices, showing a power density of 650 mW/mm at 35 GHz, with = 6 V. Index Terms-Device, HEMT, low noise, metamorphic, MHEMT, power.
Pseudomorphic InGaAs HEMTs on GaAs substrates with undoped and doped channels
Superlattices and Microstructures, 1990
A thorough investigation of the pseudomorphic HEMTs was carried out by investigating the effect of the position of the donor layer and/or doping profile ln the channel on the device performance. The PM structure's transport properties and presence of interface and bulk traps were investigated. The transistor microwave performance was measured and transconductance was compared for the various transistors. For relaxed geometry HEMTs a typical transconductance of 28OnWmm was measured.
IEEE Transactions on Electron Devices, 2001
This paper exhibits experimental and theoretical results on metamorphic high-electron mobility transistor (MM-HEMT). Modeling and measurements provide a better knowledge of device physics which allows us to optimize device structures. We present 10-GHz power performances, pulse and gate measurements, and two-dimensional (2-D) hydrodynamic modeling of enhancement-mode (E-mode) Al 0 66 In 0 34 As/Ga 0 67 In 0 33 As MM-HEMT devices. It is the first time that cap layer thickness is studied for a MM-HEMT. A typical reverse breakdown voltage of 16 V has been obtained. Gate current issued from impact ionization has been shown, for the first time, in such a device. The 2-D hydrodynamic model is a useful tool for cost engineering because it brings more information in terms of physical quantity distributions, necessary to predict breakdown behavior of FET. The 10-GHz measurements with a load-pull power set-up demonstrate the capabilities for a thick cap device with large gate-to-drain extension since an output power of 140 mW/mm have been obtained which is the state-of-the-art for such a device. These results obtained confirm the great interest of the structures for power application systems. The only work reported, to our knowledge, using a MM-HEMT structure in E-mode with an indium content close to 50% has been studied by Eisenbeiser et al.. Their typical gate-to-drain breakdown voltage was 5.2 V. The 0 6 m 3 mm devices exhibited 30 mW/mm at 850 MHz. Index Terms-Breakdown, high-electron mobility transistor (HEMT), impact ionization, metamorphic (MM).