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Electron Devices, IEEE Transactions on

Issue 3 • Date Mar 2001

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Displaying Results 1 - 25 of 33
  • Generation-recombination noise in GaN/AlGaN heterostructure field effect transistors

    Publication Year: 2001 , Page(s): 530 - 534
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    Local levels with a large activation energy Ea~0.8-1.0 eV have been observed in low-frequency noise measurements of GaN/AlGaN heterostructure field effect transistors (HFETs and MOS-HFETs) grown on 4N-SiC substrates. The noise might come from the thin (30 nm) AlGaN barrier layer. The estimates of the level parameters based on this assumption resulted in reasonable values of capture cross section σn≈(10-12-10-13) cm2 and trap concentration Nt≈5-1016 cm-3 View full abstract»

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  • Monte Carlo simulation of electron transport in the III-nitride wurtzite phase materials system: binaries and ternaries

    Publication Year: 2001 , Page(s): 535 - 542
    Cited by:  Papers (84)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    We present a comprehensive study of the transport dynamics of electrons in the ternary compounds, AlxGa1-xN and InxGa1-xN. Calculations are made using a nonparabolic effective mass energy band model. Monte Carlo simulation that includes all of the major scattering mechanisms. The band parameters used in the simulation are extracted from optimized pseudopotential band calculations to ensure excellent agreement with experimental information and ab initio band models. The effects of alloy scattering on the electron transport physics are examined. The steady state velocity field curves and low field mobilities are calculated for representative compositions of these alloys at different temperatures and ionized impurity concentrations. A field dependent mobility model is provided for both ternary compounds AlGaN and InGaN. The parameters for the low and high field mobility models for these ternary compounds are extracted and presented. The mobility models can be employed in simulations of devices that incorporate the ternary III-nitrides View full abstract»

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  • Correspondence

    Publication Year: 2001 , Page(s): 609 - 610
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (28 KB)  

    First Page of the Article
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  • Effects of annealing on Ti, Pd, and Ni/n-Al0.11Ga0.89N Schottky diodes

    Publication Year: 2001 , Page(s): 573 - 580
    Cited by:  Papers (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    Schottky diodes of Ti, Pd, and Ni/n-Al0.11Ga0.89 N have been fabricated and the barrier heights were measured to be 0.60, 0.95 and 0.97 eV using current-voltage (I-V) measurements and to be 0.67, 1.15 and 1.22 eV using capacitance-voltage (C-V) measurements. Annealed Schottky diodes are show higher I-V and C-V barrier heights when compared with as-deposited Ti Schottky diodes except high temperature annealed (450°C/30 min-500°C/1 hr) Ti Schottky diodes. The I-V barrier height of Ti/n-Al0.11Ga0.89N increases up to the annealing temperature 350°C/5 min and it decreased for higher annealing temperatures. The C-V barrier height increases up to the annealing temperature 150°C/5 min for Ti (1.63 eV), 250°C/5 min for both Pd (1.68 eV) and Ni (1.53 eV) Schottky diodes respectively. The increase of barrier heights for low temperature annealing is due to intimate contact between metal and semiconductor. Rectifying behavior has been observed up to the annealing temperature 450°C/1 hr for Ni/n-Al0.11Ga0.89N and 500°C/1 hr for both Ti and Pd/n-Al0.11Ga0.89N Schottky diodes. An increase of surface average roughness has been observed for the annealed Pd and Ni Schottky diodes except Ti Schottky diodes. Al0.11Ga 0.89N surface behaves more like ceramic with both Pd and Ni than semiconductor View full abstract»

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  • Microwave performance of AlGaN/GaN metal insulator semiconductor field effect transistors on sapphire substrates

    Publication Year: 2001 , Page(s): 416 - 419
    Cited by:  Papers (62)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (88 KB)  

    Metal-insulator-semiconductor field effect transistors (MISFETs) from surface-passivated undoped AlGaN/GaN heterostructures on sapphire were fabricated. Measured static output characteristics includes full channel currents (Idss) of roughly 750 mA/mm with gate-source pinchoff voltages of -10 V and peak extrinsic transconductancies (gm) of 100-110 mS/mm. Increased surface roughness resulting from a gate recess process to reduce the pinchoff voltage introduces gate leakage currents in the micro-amps regime. With evidence for reduced dc-to-rf dispersion from pulsed gate transfer characteristics, these devices at 4 GHz with 28.0 V bias generated maximum output power densities of 4.2 W/mm with 14.5 dB of gain and 36% power added efficiency View full abstract»

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  • Undoped AlGaN/GaN HEMTs for microwave power amplification

    Publication Year: 2001 , Page(s): 479 - 485
    Cited by:  Papers (147)  |  Patents (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB) |  | HTML iconHTML  

    Undoped AlGaN/GaN structures are used to fabricate high electron mobility transistors (HEMTs). Using the strong spontaneous and piezoelectric polarization inherent in this crystal structure a two-dimensional electron gas (2DEG) is induced. Three-dimensional (3-D) nonlinear thermal simulations are made to determine the temperature rise from heat dissipation in various geometries. Epitaxial growth by MBE and OMVPE are described, reaching electron mobilities of 1500 and 1700 cm 2/Ns, respectively, For electron sheet density near 1×1013/cm2, Device fabrication is described, including surface passivation used to sharply reduce the problematic current slump (dc to rf dispersion) in these HEMTs. The frequency response, reaching an intrinsic ft of 106 GHz for 0.15 μm gates, and drain-source breakdown voltage dependence on gate length are presented. Small periphery devices on sapphire substrates have normalized microwave output power of ~4 W/mm, while large periphery devices have ~2 W/mm, both thermally limited. Performance, without and with Si3N4 passivation are presented. On SiC substrates, large periphery devices have electrical limits of 4 W/mm, due in part to the limited development of the substrates View full abstract»

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  • AlGaN/GaN high electron mobility transistors on Si(111) substrates

    Publication Year: 2001 , Page(s): 420 - 426
    Cited by:  Papers (21)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    AlGaN/GaN high electron mobility transistors (HEMTs) on silicon substrates have for the first time been realized using organometallic vapor phase epitaxy (OMVPE). Using 1 Ω-cm p-Si(111), these devices exhibited static output characteristics with low output conductance and isolation approaching 80 V. Under microwave rf operation, the substrate charge becomes capacitively coupled and parasitically loads these devices thereby limiting their performance. As a result, typical 0.3 μm gate length devices show a 25 GHz cutoff frequency, with near unity fmax/fT ratio and 0.55 W/mm output power. A small-signal equivalent circuit incorporating elements representing the parasitic substrate loading accurately models the measured S-parameters. Removal of the conductive substrate is one way to effectively eliminate this parasitic loading. Through backside processing, freestanding 0.4-mm HEMT membranes with no thermal management were demonstrated and exhibited a significant improvement in their fmax/fT ratio up to 2.5 at the cost of lower fT and fmax along with an almost four-fold reduction of Idss View full abstract»

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  • Spontaneous and piezoelectric polarization effects on the output characteristics of AlGaN/GaN heterojunction modulation doped FETs

    Publication Year: 2001 , Page(s): 450 - 457
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    We report on the calculation of electrical characteristics of AlGaN/GaN heterojunction field effect transistors (HFETs). The model is based on the self-consistent solution of the Schrodinger and Poisson equations coupled to a quasi-2D model for the current flow. Both single and double heterojunction devices are analyzed for [0001] or [000-1] growth directions. The onset of a parasitic p-channel for particular growth directions and alloy concentrations is also shown View full abstract»

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  • Simulation of npn and pnp AlGaN/GaN heterojunction bipolar transistors performances: limiting factors and optimum design

    Publication Year: 2001 , Page(s): 427 - 432
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (120 KB)  

    The performance capabilities of npn and pnp AlGaN/GaN heterojunction bipolar transistors have been investigated by using a drift-diffusion transport model. Numerical results have been employed to study the effect of the p-type Mg doping and its incomplete ionization on device performance. The high base resistance induced by the deep acceptor level is found to be one of the causes of limited current gain values for npn devices. Reasonable improvements of the dc current gain β are observed by realistically reducing the base thickness and consequently the transit time, in accordance with processing limitations. Base transport enhancement is predicted by the introduction of a quasi-electric field in the base. The impact of the base resistivity on high-frequency characteristics is investigated for npn AlGaN/GaN devices. Simulation results reveal the difficulty to achieve decent current gain values at high current density for pnp HBTs in common emitter configuration. Despite the high electron mobility in the n-type base that aids in reducing the base resistance, a preliminary analysis for pnp devices indicates limited rf performances caused by the reduced minority hole transport across the base View full abstract»

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  • High UV/solar rejection ratios in GaN/AlGaN/GaN p-i-n photodiodes

    Publication Year: 2001 , Page(s): 486 - 489
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB)  

    The solar-blind detection capability of heterostructure diodes employing an i-Al0.33Ga0.67N layer sandwiched between two doped GaN layers is investigated via simulations using MEDICI. It is shown that the introduction of quantum features, such as InGaN quantum wells and delta-doped regions of p-Al0.33Ge0.67N, can successfully suppress the current due to photogeneration in the low-bandgap GaN regions, leading to UV/solar rejection ratios of over three orders of magnitude View full abstract»

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  • GaN HBT: toward an RF device

    Publication Year: 2001 , Page(s): 543 - 551
    Cited by:  Papers (22)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    This paper reviews efforts to develop growth and fabrication technology for the GaN HBT. Conventional devices are grown by plasma assisted MBE on MOCVD GaN templates on sapphire. HBTs were fabricated on LEO material identifying threading dislocations as the primary source of collector-emitter leakage which was reduced by four orders of magnitude for devices on nondislocated material. Base doping studies show that the mechanism of this leakage is localized punch-through caused by compensation near the dislocation. High contact and lateral resistance in the base cause large parasitic common emitter offset voltages (from 1 to 5 V) in GaN HBTs. The effect of this voltage drop on common emitter characteristics is discussed. The combination of this voltage drop and the emitter collector leakage make Gummel and common base characteristics unreliable without verification with common emitter characteristics. The selectively regrown emitter bipolar transistor is presented with a DC current gain of 6 and early voltage greater than 400 V. The transistor operated to voltages over 70 V. This device design reduces base contact resistance, and circumvented difficulties associated with the emitter mesa etch process. The Mg memory effect in MOCVD grown GaN HBTs is discussed, and MBE grown device layers are shown to produce sharp doping profiles. The low current gain of these devices is discussed, and an HBT with a compositionally graded base is presented, as well as simulations predicting further current gain improvements with base grading View full abstract»

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  • Trapping effects and microwave power performance in AlGaN/GaN HEMTs

    Publication Year: 2001 , Page(s): 465 - 471
    Cited by:  Papers (213)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB) |  | HTML iconHTML  

    The dc small-signal, and microwave power output characteristics of AlGaN/GaN HEMTs are presented. A maximum drain current greater than 1 A/mm and a gate-drain breakdown voltage over 80 V have been attained. For a 0.4 μm gate length, an fT of 30 GHz and an fmax of 70 GHz have been demonstrated. Trapping effects, attributed to surface and buffer layers, and their relationship to microwave power performance are discussed. It is demonstrated that gate lag is related to surface trapping and drain current collapse is associated with the properties of the GaN buffer layer. Through a reduction of these trapping effects, a CW power density of 3.3 W/mm and a pulsed power density of 6.7 W/mm have been achieved at 3.8 GHz View full abstract»

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  • Very-high power density AlGaN/GaN HEMTs

    Publication Year: 2001 , Page(s): 586 - 590
    Cited by:  Papers (111)  |  Patents (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB) |  | HTML iconHTML  

    Research work focusing on the enhancement of large-signal current-voltage (I-V) capabilities has resulted in significant performance improvement for AlGaN/GaN HEMT's. 100-150 μm wide devices grown on SiC substrates demonstrated a record power density of 9.8 W/mm at 8 GHz, which is about ten times higher than GaAs-based FETs; similar devices grown on sapphire substrates showed 6.5 W/mm, which was thermally limited, 2-mm-wide devices flip-chip mounted on to AlN substrates produced 9.2-9.8 W output power at 8 GHz with 44-47% PAE. A flip-chip amplifier IC using a 4-mm device generated 14 W at 8 GHz, representing the highest CW power obtained from GaN-based integrated circuits to date View full abstract»

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  • Comparison of GaN p-i-n and Schottky rectifier performance

    Publication Year: 2001 , Page(s): 407 - 411
    Cited by:  Papers (35)  |  Patents (34)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB) |  | HTML iconHTML  

    The performance of GaN p-i-n and Schottky rectifiers fabricated on the same wafer was investigated as a function of device size and operating temperature. There was a significant difference in reverse breakdown voltage (490 V for p-i-n diodes; 347 V for the Schottky diodes) and forward turn-on voltage (~5 V for the p-i-n diodes; ~3.5 V for the Schottky diodes). Both types of device showed a negative temperature coefficient for reverse breakdown, with value -0.34±0.05 V·K-1 View full abstract»

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  • An X-band GaN HEMT power amplifier design using an artificial neural network modeling technique

    Publication Year: 2001 , Page(s): 495 - 501
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB) |  | HTML iconHTML  

    In this paper, the first gallium nitride (GaN) based high electron mobility transistor (HEMT) power amplifier design using an artificial neural network (ANN) modeling technique is presented. The ANN technique was used to model the small signal behavior of a device with a gate periphery of 1 mm and a gate length of 1 μm over the broad frequency range from 1 GHz to 26 GHz with multiple bias points, based on fitting calculated S-parameters to measured S-parameters. A single stage amplifier constructed using these parameters showed a gain of about 7 dB and an output power of 1.2 W at 8 GHz when biased at Vds = 20 V and Ids 220 mA in class AB mode. The good agreement between measured and simulated results was shown in both S-parameter modeling and in amplifier design View full abstract»

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  • Application of GaN-based heterojunction FETs for advanced wireless communication

    Publication Year: 2001 , Page(s): 517 - 523
    Cited by:  Papers (39)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB) |  | HTML iconHTML  

    We review the features of GaN-based FETs and describe their expected development direction, GaN has a high breakdown field, but this does not necessarily mean it is suitable for high-voltage and high-power applications. The main advantage is that it enables scaling down beyond the silicon MOSFET miniaturization limitation from the Maxwell-Boltzmann distribution. Thus, fine gate patterns together with a high carrier velocity make GaN-based FETs be suited for millimeter and near millimeter wavelength high-power applications. In addition, by using large-area sapphire substrates, high-performance and low-cost MMICs can be produced on GaN. We expect that such devices will be the key to future advanced wireless communication systems View full abstract»

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  • The impact of surface states on the DC and RF characteristics of AlGaN/GaN HFETs

    Publication Year: 2001 , Page(s): 560 - 566
    Cited by:  Papers (352)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB) |  | HTML iconHTML  

    GaN based HFETs are of tremendous interest in applications requiring high power at microwave frequencies. Although excellent current-voltage (I-V) characteristics and record high output power densities at microwave frequencies have been achieved, the origin of the 2DEG and the factors limiting the output power and reliability of the devices under high power operation remain uncertain. Drain current collapse has been the major obstacle in the development of reliable high power devices. We show that the cause of current collapse is a charging up of a second virtual gate, physically located in the gate drain access region. Due to the large bias voltages present on the device during a microwave power measurement, surface states in the vicinity of the gate trap electrons, thus acting as a negatively charged virtual gate. The maximum current available from a device during a microwave power measurement is limited by the discharging of this virtual gate. Passivated devices located adjacent to unpassivated devices on the same wafer show almost no current collapse, thus demonstrating that proper surface passivation prevents the formation of the virtual gate. The possible mechanisms by which a surface passivant reduces current collapse and the factors affecting reliability and stability of such a passivant are discussed View full abstract»

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  • Gallium nitride based high power heterojunction field effect transistors: process development and present status at UCSB

    Publication Year: 2001 , Page(s): 552 - 559
    Cited by:  Papers (77)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB) |  | HTML iconHTML  

    The development of GaN based devices for microwave power electronics at the University of California, Santa Barbara (UCSB), is reviewed. From 1995 to 2000, the power performance of AlGaN/GaN-on-sapphire heterojunction field effect transistors improved from 1.1 W/mm to 6.6 W/mm, respectively. Compensating the disadvantages of the low thermal conductivity of the sapphire substrate through heat management via flip chip bonding onto AlN substrates, large periphery devices with an output power of 7.6 W were demonstrated. UCSB also fabricated the first GaN based amplifier integrated circuits. Critical issues involved in the growth of high quality AlGaN/GaN heterostructures by metal-organic chemical vapor deposition and the device fabrication are discussed View full abstract»

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  • Monte Carlo simulation of THz maser based on optical phonon transit time resonance in GaN

    Publication Year: 2001 , Page(s): 438 - 443
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB) |  | HTML iconHTML  

    The linear and nonlinear analysis of microwave power amplification and generation in the terahertz (THz) frequency range is carried out by the Monte Carlo method in bulk wurtzite GaN. It is shown that a dynamic negative differential mobility persists up to 80 K due to the transit-time resonance associated with optical phonons. The generation frequency depends almost linearly on the static electric field strength and can be tuned in the wide frequency range from 0.2 to 3 THz when the electric field varies from 1 up to 12 kV/cm. The optimum amplitude of the microwave electric field generated by bulk GaN is found to be of the order of the static electric field thus leading to a significant maximum efficiency of about 1 to 1.5% for microwave power generation in the THz frequency range View full abstract»

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  • Selective area growth and characterization of AlGaN/GaN heterojunction bipolar transistors by metalorganic chemical vapor deposition

    Publication Year: 2001 , Page(s): 490 - 494
    Cited by:  Papers (13)  |  Patents (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (80 KB) |  | HTML iconHTML  

    The selective area growth (SAG) and properties of AlGaN/GaN heterojunction bipolar transistors (HBTs) grown by low-pressure metalorganic chemical vapor deposition (MOCVD) are described and analyzed. Transistors based on group III-nitride material are attractive for high-power and high-temperature applications. Much work has been focused on improving p-type material, as well as heterojunction interfaces. However, there have been very few reports on HBTs operating at room temperature, At this time, current gains for nitride-based HBTs have been limited to ~10. Selective area regrowth was applied to the growth of AlGaN/GaN HBTs to analyze its potential advantages as compared to more traditional growth techniques in order to realize improved electrical performance of the devices View full abstract»

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  • The state-of-the-art of GaAs and InP power devices and amplifiers

    Publication Year: 2001 , Page(s): 472 - 478
    Cited by:  Papers (27)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (96 KB) |  | HTML iconHTML  

    Significant investments and R&D efforts over the past two decades have established GaAs and InP electronic device technologies from substrate manufacturing to MMIC amplifier design and testing. Today, GaAs and InP HBTs and HFETs, as far as gain, efficiency, and power are concerned, dominate the whole spectrum from S- to W-band and beyond. In this paper we discuss recent advances in device technologies and survey the state of the art performance of GaAs and InP HFETs and HBTs View full abstract»

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  • Influence of AlGaN deep level defects on AlGaN/GaN 2-DEG carrier confinement

    Publication Year: 2001 , Page(s): 412 - 415
    Cited by:  Papers (16)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (60 KB)  

    We have used low energy electron-excited nanoscale luminescence spectroscopy (LEEN) to detect the defects in each layer of AlGaN/GaN HEMT device structures and to correlate their effect on two-dimensional electron gas (2-DEG) confinement. We investigated AlGaN/GaN heterostructures with different electrical properties using incident electron beam energies of 0.5 to 15 keV to probe electronic state transitions within each of the heterostructure layers. AlGaN heterostructures of 25 nm thickness and nominal 30% Al concentration grown on GaN buffer layers on sapphire substrates by plasma-assisted molecular beam epitaxy exhibited a range of polarization-induced electron densities and room temperature mobilities. In general, the spectra exhibit AlGaN band edge emission at ~3.8 eV or ~4.0 eV, GaN band edge emission at ~3.4 eV, yellow luminescence (YL) features at 2.18 eV and 2.34 eV, and a large emission in the infrared (<1.6 eV) from the GaN cap layer used to passivate the AlGaN outer surface. These heterostructures also show high strain in the 2 nm-thick GaN layer with evidence for a Franz-Keldysh red shift due to piezoelectric charging. The LEEN depth profiles reveal differences between the structures with and without 2-DEG confinement and highlight the importance of AlGaN defects in the near 2-DEG region View full abstract»

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  • AlGaN/GaN heterojunction field effect transistors grown by nitrogen plasma assisted molecular beam epitaxy

    Publication Year: 2001 , Page(s): 591 - 596
    Cited by:  Papers (16)  |  Patents (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB) |  | HTML iconHTML  

    In this work, we demonstrate state of the art performance of GaN HFETs grown on SiC by rf Nitrogen plasma assisted molecular beam epitaxy (MBE) at 10 and 20 GHz and good power scalability of these devices at 10 GHz. A single stage power amplifier built by power combining four of our 1 mm devices exhibits continuous wave output power of 22.9 W with associated power added efficiency (PAE) of 37% at 9 GHz. This is to the best of our knowledge the highest CW power and the best combination of power and PAE demonstrated to date for a GaN based microwave integrated circuit at this frequency View full abstract»

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  • Characterizations of recessed gate AlGaN/GaN HEMTs on sapphire

    Publication Year: 2001 , Page(s): 603 - 608
    Cited by:  Papers (31)  |  Patents (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB) |  | HTML iconHTML  

    A recessed gate high electron mobility transistor (HEMT) has been fabricated with AlGaN/GaN heterostructure on a sapphire substrate using metalorganic chemical vapor deposition. Capacitance-voltage (C-V) and Shubnikov-de Haas measurements have shown the formation of two-dimensional (2-D) electron gas (2DEG) at Al0.11Ga0.89N/GaN heterointerface. A 2DEG mobility 12000 cm2/V-s with a sheet carrier density 2.8×1012 cm-2 was measured on Al0.11 Ga0.89N/GaN heterostructure at 8.9 K. The recessed gate Al0.26Ga0.74N/GaN HEMT structure showed maximum extrinsic transconductance 181 mS/mm and drain-source current 1120 mA/mm for a gate length 1.5 μm at 25°C. The device exhibited stable operation characteristics at 350°C for long time (500 h). No interfacial change has been observed at metal/AlGaN interface even after 350°C for 500 h treatment. The threshold voltage of device does not depend very much on operating temperature (25 to 350°C) View full abstract»

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  • Influence of electron mobility modeling on DC I-V characteristics of WZ-GaN MESFET

    Publication Year: 2001 , Page(s): 512 - 516
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB) |  | HTML iconHTML  

    We report on the drift-diffusion based simulation of a wurtzite (WZ) GaN MESFET. The main emphasis is put on the influence of electron mobility modeling on DC current-voltage (I-V) characteristics of the WZ-GaN MESFET. Two different analytical expressions are used for the electron mobility as a function of electric field. The first model is based on a simple saturation of the steady-state drift velocity with electric field (conventional three-parameter model). The other model is more realistic since it well reproduces the drift velocity-field characteristics obtained by Monte Carlo (MC) calculations, revealing the peak drift velocity with subsequent saturation at higher electric fields. Thus, it should be implemented in the drift-diffusion model for a following device simulation. However, the MC electron transport data for WZ-GaN are influenced by the specific choice of the material and band structure parameters, resulting in a variation of drift velocity-field characteristics. In addition, it should be noted that the MC simulation also neglects crystal defects in GaN, which, for example, might lead to uncontrolled electron compensation and additional electron scattering. In the present study we show that the DC I-V characteristics of the WZ-GaN MESFET are strongly affected by the MC-like electron mobility model, in particular by the peak steady-state velocity and the shape of the velocity-field characteristics even for the same drift velocity saturation level View full abstract»

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IEEE Transactions on Electron Devices publishes original and significant contributions relating to the theory, modeling, design, performance and reliability of electron and ion integrated circuit devices and interconnects.

 

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Meet Our Editors

Acting Editor-in-Chief

Dr. Paul K.-L. Yu

Dept. ECE
University of California San Diego