Publications (15)28.22 Total impact
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Article: DC and RF characteristics of doped multichannel AlAs/sub 0.56/Sb/sub 0.44//In/sub 0.53/Ga/sub 0.47/As field effect transistors with variable gate-lengths
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ABSTRACT: Depletion-mode doped-channel field effect transistors (DCFETs) using a AlAs/sub 0.56/Sb/sub 0.44//In/sub 0.53/Ga/sub 0.47/As heterostructure with multiple channels grown by molecular beam epitaxy (MBE) on an InP substrate are presented. Devices with gate lengths ranging from 0.2 /spl mu/m to 1.0 /spl mu/m have been fabricated. Three doped In/sub 0.53/Ga/sub 0.47/As channels separated by undoped AlAs/sub 0.56/Sb/sub 0.44/ layers are used for the devices. The devices exhibit unity current gain cut-off frequencies typically between 18 GHz and 73 GHz and corresponding maximum oscillation frequencies typically between 60 GHz and 160 GHz. The multiple channel approach results in wide linearity of dc and RF performance of the device.IEEE Electron Device Letters 02/2001; · 2.85 Impact Factor -
Article: Doped multichannel AlAs<sub>0.56</sub>Sb<sub>0.44</sub>/In<sub>0.53</sub>Ga<sub>0.47</sub>As field effect transistors
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ABSTRACT: A depletion-mode doped-channel field effect transistor (DCFET) using an AlAs<sub>0.56</sub>Sb<sub>0.44</sub>/In<sub>0.53</sub>Ga<sub>0.47 </sub>As heterostructure with multiple channels and a gate-length of 1.0 μm is presented. The device structure is grown by molecular beam epitaxy and consists of three doped In<sub>0.53</sub>Ga<sub>0.47</sub>As channels separated by undoped AlAs<sub>0.56</sub>Sb<sub>0.44</sub> layers. A zero gate-bias saturation current density of 350 mA/mm, extrinsic transconductance as high as 250 mS/mm, a unity current gain cutoff frequency of 18 GHz, and a maximum oscillation frequency of 60 GHz are reported. This multiple channel approach results in wide linearity of the DC and RF performances of the deviceElectronics Letters 10/1999; 35(19):1673-1674. · 0.96 Impact Factor -
Conference Proceeding: AlAs<sub>0.56</sub>Sb<sub>0.44</sub>/In<sub>0.53</sub>Ga<sub>0.47</sub>As doped multi-channel field effect transistors
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ABSTRACT: Summary form only given. Microwave and millimeter wave amplifiers for wireless and space applications need semiconductor devices with high current density and wide gain linearity. Heterostructure-based doped channel field effect transistors (DCFETs) are very promising devices for such applications. In this work, we have grown AlAs<sub>0.56</sub>Sb<sub>0.44</sub>/In<sub>0.53</sub>Ga<sub>0.47 </sub>As lattice-matched to InP with multiple doped channels using molecular beam epitaxy (MBE) and fabricated DCFETs with variable gate length (0.2 to 1.0 μm) on the heterostructure. The multichannel structure is used to achieve a wide gain linearity as well as high current density. In this paper, we present our results of multi-channel DCFETs with variable gate lengths. To the best of our knowledge, these are the first reported results of DCFETs on the AlAsSb/InGaAs material systemDevice Research Conference Digest, 1999 57th Annual; 02/1999 -
Article: Charge-control modeling of InGaAs/InP heterojunction insulated-gate FETs
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ABSTRACT: A new charge-control model for accumulation-mode heterojunction FETs is presented, This model is used to determine the mobile charge density of the heterojunction channel as a function of the gate voltage. It is the result of a self-consistent combination of semiclassical and quantum-mechanical models. It is shown that the two models can be combined to provide a computationally simple description of the gate control of channel conductivity, and hence gate control of the FET's I - V characteristics. This merging of two modeling approaches results in a new, easily used, and generalized model with broad applicability to undoped heterostructure devices. A figure of merit called the crossover point, which is the gate voltage at which the sheet charge density in the InP cladding layer is equal to the sheet charge in the 2DEG, is defined. This crossover voltage is found to decrease with increasing InP thickness, which leads to reduced device performanceIEEE Transactions on Electron Devices 04/1993; · 2.32 Impact Factor -
Article: Highly stable microwave performance of InP/InGaAs HIGFETs
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ABSTRACT: The fabrication and microwave performance of InP/InGaAs heterojunction insulated-gate FETs (HIGFETs) using plasma-enhanced chemical vapor deposition (PECVD)-deposited SiO<sub>2</sub> as the gate insulator are discussed. Extrinsic transconductances as high as 240 mS/mm were obtained. Although these devices had a drain current drift of 20% under DC bias, when operated at 5 GHz they exhibited negligible drain current drift. The observation of high transconductance and stable microwave performance makes these HIGFETs ideal candidates for microwave power applicationsIEEE Transactions on Electron Devices 09/1990; · 2.32 Impact Factor -
Conference Proceeding: A study of insulated and passivated gate technology for InP FETs
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ABSTRACT: The effects of using a new surface passivation technique prior to PECVD SiO<sub>2</sub> deposition were studied, and the performance of the devices was correlated with the state of the interface at the gate electrode. Devices with gates made using the passivation only, passivation and subsequent SiO<sub>2</sub> deposition, and SiO<sub>2 </sub> deposition without passivation were studied for a uniformly doped n-channel InP FET. The unpassivated SiO<sub>2</sub> insulated gates produced the lowest transconductance ( g <sub>m</sub>) values: passivation prior to SiO<sub>2</sub> deposition improved the characteristics of the devices and increased g <sub>m</sub> significantly. The passivated enhanced barrier gates produced the best characteristics and the highest transconductances consistently. In general the enhanced barrier gates demonstrated twice as high transconductance values as the SiO<sub>2</sub> insulated gatesIndium Phosphide and Related Materials, 1990. Second International Conference.; 05/1990 -
Article: Low frequency and microwave characterization of submicron‐gate In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As heterojunction metal‐semiconductor field‐effect transistors grown by molecular‐beam epitaxy
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ABSTRACT: Doped‐channel i‐In 0.52 Al 0.48 As/n<sup>+</sup>‐In 0.53 Ga 0.47 As/i‐In 0.52 Al 0.48 As heterojunction metal‐semiconductor field‐effect transistors lattice matched to the InP substrates with gate lengths in the submicron range have been fabricated and characterized. The dc and microwave performance of the devices are presented in this paper. Drain current anomalities, or the kink effects, were observed at room temperatures as well as at 77 K in the dc measurements. The kinks are associated with the deep‐level electron trapping, and are not present at microwave frequencies. The dc and microwave bias points for achieving maximum transconductance are different. Normal microwave characteristics are exhibited. A compression of transconductance g m is observed in the dc measurement, while such g m degradation phenomenon does not appear at microwave frequencies. At 10 GHz, an extrinsic g m of 507 mS/mm, a current‐gain‐cutoff frequency f t of 49.5 GHz, and a power‐gain‐cutoff frequency (f max ) of 70.5 GHz were observed for a 0.25‐μm‐gate device. For a 0.3‐μm‐gate device, a g m of 545 mS/mm, an f t of 42 GHz, and an f max of 114 GHz were measured. Output conductance as low as 7.7 mS/mm was measured. A voltage gain (g m /g ds ) as high as 64 was observed. The voltage gain for measured devices is well above 20 for a wide range of bias conditions. Fabricated devices show their potential for high‐frequency operations. Further investigation of the origin of traps should result in improved low‐frequency device characteristics.Journal of Applied Physics 01/1990; · 2.17 Impact Factor -
Article: DC and RF characterization of short-gate-length InGaAs/InAlAs MODFETs
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ABSTRACT: Lattice-matched InGaAs/InAlAs MODFETs with gate lengths down to 0.15 μm have been fabricated and characterized. A large discrepancy is found between the g <sub>m</sub> measured at DC and microwave frequencies and is attributed to the finite time constant of electron emission from deep traps in the InAlAs. A maximum f <sub>T</sub> of 112 GHz is measured on a 0.15-μm gate-length device. Devices with more shallow recessed gates are found to have a 50% larger output conductance, which causes the devices to exhibit an f <sub>T </sub> that is greater than f <sub>max</sub>IEEE Transactions on Electron Devices 11/1989; · 2.32 Impact Factor -
Article: N-channel depletion-mode InP FET with enhanced barrier height gates
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ABSTRACT: The fabrication of an n-channel depletion-mode InP field-effect transistor (FET) with enhanced barrier height gates, using a surface passivation technique that substantially increases the barrier height ( Phi /sub b/=0.83 eV) of InP, is reported. The transistors demonstrate characteristics with excellent pinch-off, flat saturation, transconductance in the range of 60-68 mS/mm, and no indication of the onset of breakdown for drain-source biases in excess of 35 V. They are shown to be highly stable, with no observable drain current drift over a period of more than 24 h of testing under DC bias. The high stability and performance of these devices demonstrate the potential for the gate metallization of InP.< >IEEE Electron Device Letters 09/1989; · 2.85 Impact Factor -
Article: Dependence of current-gain cutoff frequency on gate length in submicron GaInAs/AlInAs MODFETs
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ABSTRACT: Investigates the gate length (L<sub>g</sub>) dependence of the current-gain cutoff frequency f<sub>T</sub> in lattice-matched GaInAs/AlInAs MODFETs. The transconductance is found to be relatively insensitive to gate length in this submicron regime, while the f<sub>T</sub> increases with decreasing gate length due to reduced capacitance as dictated by the charge control model. An effective saturation velocity of 1.3*10<sup>7</sup> cm/s is deduced from the f<sub>T</sub>-L<sub>g</sub> dependence. A maximum f<sub>T</sub> of 112 GHz is measured on an L<sub>g</sub>=0.15 mu m device, limited mainly by parasitic charge in the AlInAs.Electronics Letters 04/1989; · 0.96 Impact Factor -
Article: Submicron‐gate In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As heterojunction metal‐semiconductor field‐effect transistors grown by molecular beam epitaxy
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ABSTRACT: We report the dc and microwave performance of i‐InAlAs/n<sup>+</sup>‐InGaAs/i‐InAlAs heterojunction metal‐semiconductor field‐effect transistors (MESFETs) with gate lengths from 0.25 to 0.35 μm. At 10 GHz, an extrinsic transconductance (g m ) of 507 mS/mm, a current gain cutoff frequency (f t ) of 49.5 GHz, and a power gain cutoff frequency (f max ) of 70.5 GHz were observed for a 0.25 μm gate device. For a 0.3 μm gate device, a g m of 545 mS/mm, an f t of 42 GHz, and an f max of 114 GHz were measured. Output conductance as low as 7.7 mS/mm was measured. The voltage gain for measured devices is well above 20 for a wide range of bias conditions.Applied Physics Letters 04/1989; · 3.84 Impact Factor -
Article: I/V anomaly and device performance of submicrometre-gate Ga0.47In0.53As/Al0.48In0.52 As HEMT
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ABSTRACT: Discrepancies observed between the DC and RF characteristics of the Ga<sub>0.47</sub>In<sub>0.53</sub>As/Al<sub>0.48</sub>In<sub>0.52 </sub>As HEMT are presented. Owing to the deep-level electron trapping, the DC I / V curve is distorted and the DC transconductance ( g <sub>mDC</sub>) is severely compressed. The small-signal RF performance is not degraded by this low-frequency phenomenon. RF transconductance ( g <sub>mRF</sub>) of 555 mS/mm and the current gain cut-off frequency ( f <sub>t</sub>) of 102 GHz were obtainedElectronics Letters 01/1989; · 0.96 Impact Factor -
Article: Kink effect in submicrometer-gate MBE-grown InAlAs/InGaAs/InAlAs heterojunction MESFETs
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ABSTRACT: The authors report the influence of the kink effect on the DC and microwave performance of i-InAlAs heterojunction doped-channel MESFETs lattice matched to an InP substrate with submicrometer gates. Kink effects were observed at room temperature as well as at 77 K in the DC measurement. The kinks seem to be related to deep-level electron trapping, and are not present at microwave frequencies. Measured results are presented showing that the existence of kinks at low operating frequencies does not seem to degrade the microwave performance of the devices.< >IEEE Electron Device Letters 01/1989; · 2.85 Impact Factor -
Article: Undoped InP/InGaAs heterostructure insulated-gate FET's grown by OMVPE with PECVD-deposited SiO/sub 2/ as gate insulator
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ABSTRACT: The fabrication and performance of InP/InGaAs insulated-gate FETs which use a heterojunction to isolate the channel electrons from the semiconductor-insulator interface are discussed. Plasma-enhanced chemical vapor deposition (PECVD) was used to deposit SiO/sub 2/ on InP to form the gate insulator. Since the device structure is undoped, channel electrons are accumulated by the gate-induced field across the insulator. Extrinsic transconductances of 130 mS/mm (300 K) and 210 mS/mm (77 K) were achieved for 1.5- mu m gate-length devices. Gate-drain breakdown voltages in excess of 20 V were also measured.< >IEEE Electron Device Letters 11/1988; · 2.85 Impact Factor -
Article: Microwave and DC characterisation of InP/GaInAs heterostructure insulated-gate FETs employing AlInAs as gate insulator
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ABSTRACT: The authors report the DC and microwave performance of undoped InP/GaInAs heterostructure insulated-gate FETs employing undoped AlInAs as the gate insulator. Devices with a 1 μm gate length were fabricated and demonstrated extrinsic transconductances g <sub>m </sub> as high as 470 mS/mm at room temperature. Devices with a 2.5 μm gate length, suitable for microwave testing, were measured and demonstrated an extrapolated f <sub>max</sub>=16 GHzElectronics Letters 10/1988; · 0.96 Impact Factor
Top co-authors
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Institutions
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1999
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University of Illinois, Urbana-Champaign
- Department of Electrical and Computer Engineering
Urbana, IL, USA
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1989–1993
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University of Maryland, College Park
- Department of Electrical & Computer Engineering
College Park, MD, USA
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1989–1990
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Cornell University
- Department of Electrical and Computer Engineering
Ithaca, NY, USA
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