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1.
The effects of traps in GaAs MESFETs are studied using a pulsed gate measurement system. The devices are pulsed into the active region for a short period (typically 1 μs) and are held in the cutoff region for the rest of a 1-ms period. While the devices are on, the drain current is sampled and a series of pulsed gate I -V curves are obtained. The drain current obtained under the pulsed gate conditions for a given V GS and V DS gives a better representation of the instantaneous current for a corresponding V gs and V ds in the microwave cycle because of the effects of traps. The static and pulsed gate curves were used in a nonlinear time-domain model to predict harmonic current. The results showed that analysis using pulsed gate curves yielded better predictions of harmonic distortion than analysis based on conventional state I -V curves under large-signal conditions 相似文献
2.
Self-aligned high-frequency InP/InGaAs double heterojunction bipolar transistors (DHBTs) have been fabricated on a Si substrate. A current gain of 40 was obtained for a DHBT with an emitter dimension of 1.6 μm×19 μm. The S parameters were measured for various bias points. In the case of I C=15 mA, f T was 59 GHz at V CE=1.8 V, and f max was 69 GHz at V CE=2.3 V. Due to the InP collector, breakdown voltage was so high that a V CE of 3.8 V was applied for I C=7.5 mA in the S -parameter measurements to give an f T of 39 GHz and an f max of 52 GHz 相似文献
3.
Greenberg D.R. del Alamo J.A. Harbison J.P. Florez L.T. 《Electron Device Letters, IEEE》1991,12(8):436-438
Molecular beam epitaxy (MBE)-grown L g=1.7-μm pseudomorphic Al0.38Ga0.62As/n+-In0.15Ga 0.85As metal-insulator-doped channel FETs (MIDFETs) are presented that display extremely broad plateaus in both f T and f max versus V GS, with f T sustaining 90% of its peak over a gate swing of 2.6 V. Drain current is highly linear with V GS over this swing, reaching 514 mA/mm. No frequency dispersion in g m up to 3 GHz was found, indicating the absence of electrically active traps in the undoped AlGaAs pseudoinsulator layer. These properties combine to make the pseudomorphic MIDFET highly suited to linear, large-signal, broadband applications 相似文献
4.
《Electron Devices, IEEE Transactions on》1990,37(1):153-158
The fabrication of a silicon heterojunction microwave bipolar transistor with an n+ a-Si:H emitter is discussed, and experimental results are given. The device provides a base sheet resistance of 2 kΩ/□ a base width 0.1 μm, a maximum current gain of 21 (V CE=6 V, I c=15 mA), and an emitter Gummel number G E of about 1.4×1014 Scm-4. From the measured S parameters, a cutoff frequency f t of 5.5 GHz and maximum oscillating frequency f max of 7.5 GHz at V CE=10 V, I c=10 mA are obtained 相似文献
5.
A quantitative physical model for calculating the hot-electron injection probability, I G/I SUB, for both buried and surface p-channel MOSFETs is presented. The model utilizes the two-dimensional potential contours generated by PISCES, and integrates the probability of substrate hot-electron injection across the high-field region near the drain. The known phenomenon that buried-channel (BC) PMOS has higher hot-electron injection probability but lower channel field (I SUB/I D) than a similar surface-channel (SC) device is successfully modeled. This phenomenon can be attributed to the larger energy band hump-up near the drain and the larger oxide field (and thus greater barrier lowering) at a given bias condition for the buried-channel device. The I G characteristics can be obtained from the calculated I G /I SUB ratio, using readily available I SUB values 相似文献
6.
The usual approximate expression for measured f T =[g m/2π (C gs+C gd)] is inadequate. At low drain voltages just beyond the knee of the DC I -V curves, where intrinsic f t is a maximum for millimeter-wave MODFETs, the high values of C gd and G ds combine with the high g m to make terms involving the source and drain resistance significant. It is shown that these resistances can degrade the measured f T of a 0.30-μm GaAs-AlGaAs MODFET from an intrinsic maximum f T value of 73 GHz to a measured maximum value of 59 GHz. The correct extraction of maximum f T is essential for determining electron velocity and optimizing low-noise performance 相似文献
7.
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
8.
The authors show that the Taylor-series coefficients of a FET's gate/drain I /V characteristic, which is used to model this nonlinearity for Volterra-series analysis, can be derived from low-frequency RF measurements of harmonic output levels. The method circumvents many of the problems encountered in using DC measurements to characterize this nonlinearity. This method was used to determine the incremental gate I /V characteristic of a packaged Aventek AT10650-5 MESFET biased at a drain voltage of 3 V and drain current of 20 mA. The FET's transconductance was measured at DC, and its small-signal equivalent circuit (including the package parasitics) was determined by adjusting its circuit element values until good agreement between calculated and measured S parameters was obtained. The FET was then installed in a low-frequency test fixture. Excellent results were obtained 相似文献
9.
The optical power emitted by a monomode GaAlAs laser is filtered with a monochromator. The 1/f noise in the filtered emission is found to be directly dependent on the noncoherent emission, such as S pαP ncm. Here s p is the spectral density of the 1/f fluctuations, P nc is the average noncoherent power, m =3/2 under spontaneous emission, and m =4 in the superradiation and laser regions. Study of the 1/f noise in the optical power in a band centered at the laser wavelength and with variable bandwidth shows three operating regions. (1) LED region (at low currents): the fluctuations with a 1/f spectrum are uncorrelated in wavelength. (2) Superradiation region (at currents close to the threshold): the fluctuations are correlated. (3) Laser region: the 1/f noise apparently is dominated by noncoherent emission within a small optical band around the laser wavelength 相似文献
10.
A simplified analytical expression for the temperature dependent saturated I D-V D characteristics of hydrogenated amorphous silicon (a-Si:H) thin-film transistors, between -50°C and 90°C, is presented and experimentally verified. The results show that the experimental transfer and output characteristics at several temperatures are easily modeled by a single equation. The model is based on three functions obtained from the experimental data of I D versus V G, over a range of temperature. Theoretical results confirm the simple form of the model in terms of the device geometry. As the temperature increased, the saturated drain current increased and, at a fixed gate voltage the device saturated at increasingly larger drain voltages while the threshold voltage decreased. Good agreement between the measured data and the model was obtained up to 363 K. Also observed at temperatures larger than 363 K was a decrease in I D and more severe gate voltage hysteresis characteristics 相似文献
11.
Magneto-transport and cyclotron resonance measurements were made to determine directly the density, mobility, and the effective mass of the charge carriers in a high-performance 0.15-μm gate In0.52 Al0.48As/In0.53Ga0.47As high-electron-mobility transistor (HEMT) at low temperatures. At the gate voltage V G=0 V, the carrier density n g under the gate is 9×1011 cm-2, while outside of the gate region n g=2.1×1012 cm-2. The mobility under the gate at 4.2 K is as low as 400 cm2/V-s when V G<0.1 V and rapidly approaches 11000 cm2/V-s when V G>0.1 V. The existence of this high mobility threshold is crucial to the operation of the device and sets its high-performance region in V G>0.1 V 相似文献
12.
The observed 1/f noise in the light-output power S p of four different types of heterostructure lasers is explained in terms of spatially uncorrelated gain fluctuations and spontaneous emission fluctuations. Two possible noise sources are suggested: fluctuations in the absorption coefficient and fluctuations in the number of free carriers. Both models are in agreement with the experimental results obtained from index-guided and gain-guided diodes at wavelengths of 1.3 and 0.8 μm. The dependence S p ∝P m has been observed with P the average light-output power and m =3/2 under spontaneous emission, a small transition region with m =5/2, m =4 in the superradiation region, and 0⩽m ⩽1 in the laser region 相似文献
13.
An experimental technique for accurately determining both the inversion charge and the channel mobility μ of a MOSFET is presented. With this new technique, the inversion charge is measured as a function of the gate and drain voltages. This improvement allows the channel mobility to be extracted independent of drain voltage V DS over a wide range of voltages (V DS=20-100 mV). The resulting μ(V GS) curves for different V DS show no drastic mobility roll-off at V GS near V TH. This suggests that the roll-off seen in the mobility data extracted using the split C - V method is probably due to inaccurate inversion charge measurements instead of Coulombic scattering 相似文献
14.
Fang P. Hall J. Chen T.M. Dekker A.J. Van der Ziel A. 《Electron Device Letters, IEEE》1990,11(5):212-214
Experiments in which a normal-to-superconducting (NS) boundary is created in an originally superconducting bar of bulk YBa2Cu 3O7-x is described. The first noise measurements associated with such a boundary are presented. A high-density (5.20 g-cm -3) sample (sample A) and a low density (4.23 g-cm-3 ) sample (sample B) have been investigated. Common to both samples is 1/f 2 noise observed in the frequency region between about 15 and 50 Hz that can be associated with the NS boundary itself. Sample A also exhibits conventional 1/f noise as expected for the normal part of the boundary, below about 15 Hz. In contrast, sample B shows 1/f 1.5 noise in this region; since the sample contains considerably fewer small grains than sample A, any 1/f noise is presumably masked in B. It is suggested that the 1/f 2 noise might be associated with flux-flow noise 相似文献
15.
A simple method is proposed for extracting the electrical parameters of a silicon-on-insulator (SOI) material from a depletion-mode MOSFET. It is based on an analysis of static input current-voltage I D(V G) and transconductance-voltage g m(V G) characteristics in the linear region. Functions varying linearly with gate voltage are constructed from I D(V G) and g m(V G) functions. These new functions allow a straightforward determination of the parameters usually obtained from a capacitance-voltage measurement (doping level, oxide charge, etc.) and also the bulk-layer and accumulation-layer carrier mobility 相似文献
16.
Monte Carlo methods are used to compare electronic transport and device behavior in n+-AlxGa1-xAs/GaAs modulation-doped field-effect transistors (MODFETs) at 300 K for x =0.10, 0.15, 0.22, 0.30, 0.35, and 0.40. The differences between the x =0.22 and x =0.30 MODFETs with respect to parasitic conduction in AlxGa1-xAs, gate currents, and switching times, are of particular interest. The donor-related deep levels in AlxGa1-xAs, are disregarded by assuming all donors to be fully ionized, and the focus is only on the confinement and transport of the carriers. The following quantities are studied in detail: transfer characteristics (I D versus V G), transconductance (g m), switching speeds (τON), parasitic conduction in AlxGa 1-xAs, gate current (I G), average electron velocities and energies in GaAs and AlxGa1-x As, electron concentration in the device domain, k -space transfer (to low mobility L and X valleys), and details of the real-space transfer process 相似文献
17.
Gate-voltage-dependent mobility profiles in long-, short-, wide-, and narrow-channel WNx-BPLDD (buried p-type buffer lightly doped drain region) GaAs MESFETs have been determined (L G =10, 4, 2, 1, 0.8, 0.5, 0.3 μm, W G=20 μm; W G-100, 40, 20, 10, 4, 2 μm, L G=0.5 μm). The mobility mainly depends on the channel width, while the gate length has much less influence. Thus, using proper gate dimensions the channel mobility can be tuned. The highest drift mobility values agree quite well with the measured Hall mobilities. Mobility profiles of large-area MESFETs are probably degraded by the WN x-gate fabrication process. Injected excess charges at gate length below 0.5 μm distorts the mobility evaluations 相似文献
18.
Yiqi Zhuang Qing Sun 《Electron Devices, IEEE Transactions on》1991,38(11):2540-2547
Accelerated life tests with high-temperature storage and electric aging for n+-p-n silicon planar transistors were carried out. Current gain h FE increases monotonously with time during the tests, and the h FE drift is correlated with initial measured 1/f noise in the transistors, i.e. the drift amount significantly increases with the increase of noise level. The correlation coefficient of relative drift Δh FE /h FE and 1/f noise spectral density S iB(f ) is far larger than that of Δ h FE/h FE and initial DC parameters of the transistors. A quantitative theory model for the h FE drift has been developed and explains the h FE drift behavior in the tests, which suggests that the h FE drift and 1/f noise can be attributed to the same physical origin, and both are caused by the modulation of the oxide traps near the Si-SiO2 interface to Si surface recombination. 1/f noise measurement, therefore, may be used as a fast and nondestructive means to predict the long-term instability in bipolar transistors 相似文献
19.
An In0.41Al0.59As/n+-In0.65 Ga0.35As HFET on InP was designed and fabricated, using the following methodology to enhance device breakdown: a quantum-well channel to introduce electron quantization and increase the effective channel bandgap, a strained In0.41Al0.59As insulator, and the elimination of parasitic mesa-sidewall gate leakage. The In0.65Ga0.35As channel is optimally doped to N D=6×1018 cm-3. The resulting device (L g=1.9 μm, W g =200 μm) has f t=14.9 GHz, f max in the range of 85 to 101 GHz, MSG=17.6 dB at 12 GHz V B=12.8 V, and I D(max)=302 mA/mm. This structure offers the promise of high-voltage applications at high frequencies on InP 相似文献
20.
Poly-Si resistors with an unimplanted channel region (and with n-type source/drain regions) can exhibit a nonhyperbolic sine (non-sinh) I -V characteristic at low V DS and an activation energy which is not simply decreasing monotonically with increasing V DS. These phenomena are not explained by conventional poly-Si resistor models. To describe these characteristics, a self-consistent model which includes the effects of a reverse-biased diode at the drain end is presented. Numerical simulation results show excellent agreement with experiment in regard to the shape of the I -V characteristic and of the effective activation energy as a function of V DS 相似文献