共查询到20条相似文献,搜索用时 31 毫秒
1.
Wang G.W. Feng M. Kaliski R. Liaw Y.P. Lau C. Ito C. 《Electron Device Letters, IEEE》1989,10(10):449-451
The authors present the fabrication and characterization of ion-implanted graded InxGa1-xAs/GaAs MESFETs. The InxGa1-xAs layers are grown on GaAs substrates by MOCVD (metal-organic chemical vapor deposition) with InAs concentration graded from 15% at the substrate to 0% at the surface. 0.5-μm gate MESFETs are fabricated on these wafers using silicon ion implantation. In addition to improved Schottky contact, the graded InxGa 1-xAs MESFET achieves maximum extrinsic transconductance of 460 mS/mm and a current-gain cutoff frequency f t of 61 GHz, which is the highest ever reported for a 0.5-μm gate MESFET. In comparison, In0.1Ga0.9As MESFETs fabricated with the same processing technique show an f t of 55 GHz 相似文献
2.
The fabrication and characterization of a 0.25-μm-gate, ion-implanted GaAs MESFET with a maximum current-gain cutoff frequency f t of 126 GHz is reported. Extrapolation of current gains from bias-dependent S -parameters at 70-100% of I dss yields f 1's of 108-126 GHz. It is projected that an f 1 of 320 GHz is achievable with 0.1-μm-gate GaAs MESFETs. This demonstration of f 1's over 100 GHz with practical 0.25-μm gate length substantially advances the high-frequency operation limits of short-gate GaAs MESFETs 相似文献
3.
Charache G.W. Akram S. Maby E.W. Bhat I.B. 《Electron Devices, IEEE Transactions on》1997,44(11):1837-1842
The metal semiconductor field effect transistor (MESFET) represents a more realistic test for “passivation” efficacy than conventional capacitor test structures due to its prototypical fabrication process. This paper evaluates Gallium-Arsenide (GaAs) surface passivation films utilizing the MESFET as a test vehicle. For this study, gate-to-drain leakage current, gate-to-drain breakdown voltage, complex impedance versus frequency, and low-frequency noise measurements are performed on MESFETs with various passivation films. The results indicate that a hydrogen plasma used to “pre-clean” the GaAs surface in conjunction with an in situ plasma-enhanced chemical vapor deposition (PECVD) Si3N4 passivation film yields the best performance. In contrast, atomic-layer-epitaxial ZnSe demonstrated inferior performance (even in comparison to PECVD Si3N4 passivation films that did not receive a hydrogen “pre-clean”) 相似文献
4.
Breakdown of overlapping-gate GaAs MESFETs 总被引:1,自引:0,他引:1
Chang-Lee Chen 《Electron Devices, IEEE Transactions on》1996,43(4):535-542
Gate-breakdown mechanisms in GaAs MESFETs have been studied by numerical simulation. The devices simulated include normal passivated and unpassivated MESFETs as well as overlapping-gate MESFETs passivated with low-temperature-grown (LTG) GaAs, normal GaAs, and silicon dioxide. The breakdown voltage is the highest for the overlapping-gate MESFET with LTG GaAs passivation, which agrees with the experimental results reported previously. The high breakdown voltage is the result of an altered electric field near the drain-edge of the Schottky-contact gate. This field modification is achieved most effectively by using an overlapping gate structure. The LTG GaAs is the best passivation layer because of its high resistivity and breakdown-field strength 相似文献
5.
A microwave technique was used to determine the electron drift velocity in an ion-implanted GaAs MESFET with a 0.5×100-μm gate. The characteristics of the velocity versus drain-to-source voltage for a GaAs MESFET exhibit a peak velocity of 4.0, 3.3, and 2.2×10 7 cm/s at 100%, 65%, and 31% of I dss, respectively. This work presents the first experimental determination of electron drift velocity at various gate biases and provides verification for velocity overshoot in ion-implanted GaAs MESFETs 相似文献
6.
Lau C.L. Feng M. Lepkowski T.R. Wang G.W. Chang Y. Ito C. 《Electron Device Letters, IEEE》1989,10(9):409-411
Ion-implanted GaAs MESFETs with half-micrometer gate length have been fabricated on 3-in-diameter GaAs substrates. At 16 GHz, a minimum noise figure of 0.8 dB with an associated gain of 6.3 dB has been measured. This noise figure is believed to be the lowest ever reported for 0.5- and 0.25-μm ion-implanted MESFETs, and is comparable to that for 0.25-μm HEMTs at this frequency. By using the Fukui equation and the fitted equivalent circuit model, a K f factor of 1.4 has been obtained. These results clearly demonstrate the potential of ion-implanted MESFET technology for K -band low-noise integrated circuit applications 相似文献
7.
Yin L.-W. Hwang Y. Lee J.H. Kolbas R.M. Trew R.J. Mishra U.K. 《Electron Device Letters, IEEE》1990,11(12):561-563
A metal-semiconductor field-effect transistor (MESFET) utilizing surface layers of GaAs grown at a low temperature by MBE (LT GaAs) under the gate electrode has been fabricated. The high trap density of LT GaAs reduces the surface fields of the FET, suppresses gate leakage, and increases the gate-drain breakdown voltage without sacrificing current drive capability. An undoped AlAs layer is incorporated between the LT GaAs layer and the channel as a barrier to the diffusion of excess As from the LT GaAs layer to the channel. A 74-μm-gate-width device demonstrated an improved breakdown voltage of 34.85 V with a g m of 144 mS/mm and an I dss of 248 mA/mm 相似文献
8.
A study of the high-frequency performance of short-gate ion-implanted GaAs MESFETs with gate lengths of 0.3 and 0.5 μm is discussed. Excellent DC and microwave performance have been achieved with an emphasis on the reduction of effective gate length during device fabrication. From f t of 83 and 48 GHz for 0.3-0.5-μm gate devices, respectively, an electron velocity of 1.5×107 cm/s is estimated. An f t of 240 GHz is also projected for a 0.1-μm-gate GaAs MESFET. These experimental results are believed to be comparable to those of the best HEMTs (high-electron-mobility transistors) reported and higher than those generally accepted for MESFETs 相似文献
9.
GaAs MESFETs (metal-epitaxial-semiconductor-field-effect transistors) with ion-implanted active channels have been fabricated on 3-in-diameter GaAs substrates which demonstrate device performance comparable with that of AlGaAs/InGaAs pseudomorphic HEMT (high-electron-mobility transistor) devices. Implanted MESFETs with 0.5-μm gate lengths exhibit an extrinsic transconductance of 350 mS/mm. From S -parameter measurements, a current-gain cutoff frequency f 1 of 48 GHz and a maximum-available-gain cutoff frequency f max greater than 100 GHz are achieved. These results clearly demonstrate the suitability of ion-implanted MESFET technology for millimeter-wave discrete device, high-density digital, and monolithic microwave and millimeter-wave IC applications 相似文献
10.
McDermott M.G. Sweeney C.N. Benedek M. Borelli J.J. Dawe G. Raffaelli L. 《Microwave Theory and Techniques》1990,38(9):1183-1190
Two technologies are demonstrated whereby high-Q , vertical-structure, abrupt-junction varactor diodes are monolithically integrated with 0.25-μm GaAs MESFETs on semi-insulating GaAs substrates for multifunction millimeter-wave monolithic circuit applications. Diodes with various anode sizes have been realized with measured capacitance swings of >2.1:1 from 0 V to -4 V and series resistances of approximately 1 Ω. Diodes having a zero bias capacitance of 0.35 pF have Q 's of >19000 (50 MHz) with -4 V applied to the anode. Under power bias conditions, the MESFETs have a measured gain of >6 dB at 35 GHz with extrapolated values for f t and f max of 32 GHz and 78 GHz, respectively. Using these technologies, a monolithic Ka -band voltage controlled oscillator (VCO) containing a varactor diode, a 0.25-μm GaAs MESFET, and the usual MMIC passive components has been built and tested. At around 31 GHz, the circuit has demonstrated 60-mW power output with 300 MHz of tuning bandwidth 相似文献
11.
The authors report on advanced ion implantation GaAs MESFET technology using a 0.25-μm `T ' gate for super-low-noise microwave and millimeter-wave IC applications. The 0.25×200-μm-gate GaAs MESFETs achieved 0.56-dB noise figure with 13.1-dB associated gain at 50% I DSS and 0.6 dB noise figure with 16.5-dB associated gain at 100% I DSS at a measured frequency of 10 GHz. The measured noise figure is comparable to the best noise performance of AlGaAs/GaAs HEMTs and AlGaAs/InGaAs/GaAs pseudomorphic HEMTs 相似文献
12.
Short-channel effects, substrate leakage current, and average electron velocity are investigated for 0.1-μm-gate-length GaAs MESFETs fabricated using the SAINT (self-aligned implantation for n+-layer technology) process. The threshold-voltage shift was scaled by the aspect ratio of the channel thickness to the gate length ( a /L g). The substrate leakage current in a sub-quarter-micrometer MESFET is completely suppressed by the buried p layers and shallow n+-layers. The average electron velocity for 0.1- to 0.2-μm-gate-length FETs is estimated to be 3×106 cm/s from the analysis of intrinsic FET parameters. This high value indicates electron velocity overshoot. Moreover, a very high f T of 93.1 GHz has been attained by the 0.1-μm SAINT MESFET 相似文献
13.
Dependence of ionization current on gate bias in GaAs MESFETs 总被引:1,自引:0,他引:1
Canali C. Neviani A. Tedesco C. Zanoni E. Centronio A. Lanzieri C. 《Electron Devices, IEEE Transactions on》1993,40(3):498-501
The nonmonotonic behavior of gate current I g as a function of gate-to-source voltage V gs is reported for depletion-mode double-implant GaAs MESFETs. Experiments and numerical simulations show that the main contribution to I g (in the range of drain biases studied) comes from impact-ionization-generated holes collected at the gate electrode, and that the bell shape of the I g(V gs) curve is strongly related to the drop of the electric field in the channel of the device as V gs is moved towards positive values 相似文献
14.
These devices have a planar structure with the channel and gate regions formed by the selective implantation of silicon and beryllium into an Fe-doped semi-insulating InP substrate. The nominal gate length is 2 μm with a channel doping of 1017 cm-3 and thickness of 0.2 μm. The measured values of f T and f max are 10 and 23 GHz, respectively. Examination of the equivalent circuit parameters and their variation with bias led to the following conclusions: (a) a relatively gradual channel profile results in lower than desired transconductance, but also lower gate-to-channel capacitance; (b) although for the present devices, the gate length and transconductance are the primary performance-limiting parameters, the gate contact resistance also reduces the power gain significantly; (c) the output resistance appears lower than that of an equivalent GaAs MESFET, and requires a larger V DS to reach its maximum value; and (d) a dipole layer forms and decouples the gate from the drain with a strength that falls between that of previously reported GaAs MESFETs and InP MESFETs 相似文献
15.
A self-backgating GaAs MESFET model which can simulate low-frequency anomalies has been developed by including deep-level trap effects. These cause transconductance reduction due to electron emission from EL2 in the depletion width change at the edge of the Schottky gate junction and the output conductance to increase due to the time-dependent net negative charge concentration in the semi-insulating substrate as a result of self-backgating with the applied signal frequency. This model has been incorporated in PSPICE and includes a time-dependent I -V curve model, a capacitance model, an RC network describing the effective substrate-induced capacitance and resistance, and a switching resistance providing device symmetry. An analytical capacitance model describes the dependence of capacitance on V gs and V ds and includes the channel-substrate junction modulation by the self-backgating effect. A transit-time delay is also included in the transconductances, g m and g mbs, for model accuracy and to describe the phase shift of S-parameters. Measured data correspond to simulations by this model of the low-frequency anomalous characteristics, voltage-dependent capacitances, and S-parameters of conventional GaAs MESFETs for linear and microwave circuit design 相似文献
16.
We present a theoretical study of metal-semiconductor field-effect transistor (MESFET) devices for three different materials: zincblende-phase gallium nitride (ZB-GaN), cubic-phase silicon carbide (3C-SiC) and gallium arsenide (GaAs). The dc breakdown voltage of comparable MESFETs made with the two wide bandgap materials, ZB-GaN and 3C-SiC are compared to that made with the well studied material, GaAs. In this way, the GaAs calculations serve as a control, enabling an accurate comparison of the device behaviors. The simulations are performed with a new, generalized, self-consistent, full-band Monte Carlo simulator. The new simulator includes fully numerical scattering rates and a fully numerical, overlap-based final-state selection process. A 0.1 /spl mu/m gate-length MESFET is used for all of the simulations, and rectangular wells of lightly doped material are used to model interface states. The calculated dc breakdown voltages of the ZB-GaN, 3C-SiC, and GaAs MESFETs are 18, 16, and 5 V respectively. The previously estimated factor-of-four difference between the breakdown voltage of ZB-GaN and GaAs devices is verified. 相似文献
17.
A high-transconductance n-channel, depletion-mode InGaAs metal-semiconductor field-effect transistor (MESFET) with a Langmuir-Blodgett deposited gate fabricated on organometallic chemical vapor deposition (OMCVD)-grown InGaAs lattice matched to InP is reported. The fabrication process is similar to epitaxial GaAs FET technology and is suitable for making optoelectronic integrated circuits (OEICs) for long-wavelength fiber-optic communications systems. Devices with 1-μm gate and 6×1016 channel doping achieved 162-mS/mm extrinsic transconductance and -1.8-V pinch-off voltage. The effective saturation velocity of electrons in the channel was measured to be between 3.5 and 3.9×107 cm/s. The drain current ( I dss), 300 mA/mm at V ds=2.5 V, is the highest current capability reported for depletion-mode InGaAs MESFET devices with low pinch-off voltages 相似文献
18.
A wide-bandwidth GaAs MESFET operational amplifier is reported, with a 65-dB DC gain and a 20-GHz gain-bandwidth product at 500 MHz. The circuit uses a variety of local feedback techniques to enhance the overall gain. The use of an undoped GaAs buffer, grown at a relatively low temperature (≈300°C), eliminates backgating and light sensitivity. The circuit was fabricated in an 80-GHz f T MESFET process, with 0.2-μm electron-beam defined gates. The high levels of 1/f noise, MESFET frequency-dependent output conductance, and large offset voltage standard deviation limit the application of the circuit to moderate precision applications 相似文献
19.
Ren F. Hobson W.S. Pearton S.J. Oster L.J. Smith P.R. 《Electron Device Letters, IEEE》1989,10(8):389-390
The fabrication of GaAs MESFET's with 0.9-μm gate length on InP substrates, after growth of the heteroepitaxial material by metalorganic chemical vapor deposition (MOCVD) is described. The MESFETs exhibit extrinsic transconductances of 377 mS-mm-1, the highest value yet reported for GaAs-on-InP devices. The drain I -V characteristic shows excellent saturation, a knee voltage of 0.75 V, and no light sensitivity. A unity current-gain cutoff frequency of 22 GHz and a maximum frequency of oscillation of 30 GHz are obtained for these MESFETs 相似文献
20.
The commenter points out a discrepancy between the results in the above-titled paper (ibid., vol.13, p.149-51, 1992) and those of C.P. Lee et al. (ibid., vol. EDL-3, p.97-8, 1982). He emphasizes that trap-fill-limited (TFL) conduction and trap-impact ionization are important mechanisms causing high substrate leakage current and backgating effect of GaAs MESFETs. He suggests that the dependence of the backgating and leakage current threshold voltage V BGT on the source-to-drain bias V DS of the MESFET can be used to experimentally evaluate if the observed backgating effect and leakage current are caused by mechanisms related to n-i-n or Schottky-i-n structures. The authors, in reply, amplify on the commenter's remarks and explain the discrepancy 相似文献