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Electron Device Letters, IEEE

Issue 9 • Date Sept. 2009

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Displaying Results 1 - 25 of 45
  • Table of contents

    Publication Year: 2009 , Page(s): C1 - 894
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    Freely Available from IEEE
  • IEEE Electron Device Letters publication information

    Publication Year: 2009 , Page(s): C2
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  • Multigate GaN RF Switches With Capacitively Coupled Contacts

    Publication Year: 2009 , Page(s): 895 - 897
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (229 KB) |  | HTML iconHTML  

    We present the analysis and the performance characteristics of novel III-Nitride multigate (MG) radio-frequency (RF) switches fabricated over AlGaN/GaN heterostructures using capacitively coupled contacts (C3). C3 device technology does not require contact annealing and, thus, allows for fully self-aligned processing of MG devices with tight electrode spacing. The combination of C3 electrodes with MG RF switch design results in devices with significantly lower OFF-state capacitance, higher isolation, and higher RF switching power as compared to conventional FET-based RF switches. View full abstract»

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  • Integrated Hydrogen-Sensing Amplifier With GaAs Schottky-Type Diode and InGaPGaAs Heterojunction Bipolar Transistor

    Publication Year: 2009 , Page(s): 898 - 900
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (313 KB) |  | HTML iconHTML  

    New hydrogen-sensing amplifiers are fabricated by integrating a GaAs Schottky-type hydrogen sensor and an InGaP-GaAs heterojunction bipolar transistor. Sensing collector currents (ICN and ICH) reflecting to N2 and hydrogen-containing gases are employed as output signals in common-emitter characteristics. Gummel-plot sensing characteristics with testing gases as inputs show a high sensing-collector-current gain (ICH/ICN) of > 3000. When operating in standby mode for in situ long-term detection, power consumption is smaller than 0.4 ??W. Furthermore, the room-temperature response time is 85 s for the integrated hydrogen-sensing amplifier fabricated with a bipolar-type structure. View full abstract»

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  • AlGaN/GaN HEMT With Integrated Recessed Schottky-Drain Protection Diode

    Publication Year: 2009 , Page(s): 901 - 903
    Cited by:  Papers (15)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (425 KB) |  | HTML iconHTML  

    We present an AlGaN/GaN high-electron mobility transistor (HEMT) with an integrated recessed protection diode on the drain side of the transistor channel. Results from our Schottky-drain HEMT demonstrate an excellent reverse blocking with minor tradeoff in the on-state resistance for the complete device. The excellent quality of the forward diode characteristics indicates high robustness of the recess process. The reverse blocking capability of the diode is better than - 110 V. Physical-based device simulations give an insight in the respective electronic mechanisms. This is the first time that a recessed Schottky-drain diode integrated in a HEMT device is presented. View full abstract»

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  • Gate-Recessed InAlN/GaN HEMTs on SiC Substrate With  \hbox {Al}_{2}\hbox {O}_{3} Passivation

    Publication Year: 2009 , Page(s): 904 - 906
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (403 KB) |  | HTML iconHTML  

    We studied submicrometer (LG = 0.15-0.25 ??m) gate-recessed InAlN/AlN/GaN high-electron mobility transistors (HEMTs) on SiC substrates with 25-nm Al2O3 passivation. The combination of a low-damage gate-recess technology and the low sheet resistance of the InAlN/AlN/GaN structure resulted in HEMTs with a maximum dc output current density of IDS,max = 1.5 A/mm and a record peak extrinsic transconductance of gm,ext = 675 mS/mm. The thin Al2O3 passivation improved the sheet resistance and the transconductance of these devices by 15% and 25%, respectively, at the same time that it effectively suppressed current collapse. View full abstract»

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  • Electrical Characteristics of \hbox {Al}_{2} \hbox {O}_{3}/\hbox {TiO}_{2}/\hbox {Al}_{2}\hbox {O}_{3} Nanolaminate MOS Capacitor on p -GaN With Post Metallization Annealing and (\hbox {NH}_{4})_{2}\hbox {S}_{X} Treatments

    Publication Year: 2009 , Page(s): 907 - 909
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (310 KB) |  | HTML iconHTML  

    In this letter, electrical characteristics of nanolaminate Al2 O3/TiO2/Al2O3 on p-GaN MOS capacitor with and without PMA and (NH4)2 SX treatments were investigated. I-V and C-V characteristics were improved by both PMA and (NH4)2SX treatments. The leakage-current densities can be improved to 3.0 ?? 10-8 and 2.2 ?? 10-8 A/cm2 at ??1 V, respectively. Almost an ideal C-V curve, the effective dielectric constant of 12.1 and the averaged Dit value of 4.3 ?? 1011 eV-1 ?? cm-2 were obtained. View full abstract»

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  • MOCVD-Grown AlGaN Buffer GaN HEMTs With V-Gates for Microwave Power Applications

    Publication Year: 2009 , Page(s): 910 - 912
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (347 KB) |  | HTML iconHTML  

    We report the performance of AlGaN buffer GaN high-electron mobility transistors (HEMTs) grown by metal-organic chemical vapor deposition. GaN HEMTs on high-quality AlGaN buffer were grown on SiC substrates. The incorporation of an AlGaN buffer into the GaN HEMT significantly improves channel confinement and suppresses the short-channel effect. Advanced deep-recess V-gate structures were employed to optimize the device for better microwave power performance. With a 10- nm GaN channel layer sandwiched between the AlGaN barrier and buffer, excellent power performance was achieved. The output power density is 13.1 W/mm, and the associated power-added efficiency is 72% at 4-GHz frequency and 48- V drain bias. This power performance is comparable to the state-of-the-art GaN HEMTs grown on GaN buffers, indicating that the AlGaN buffer in our optimized device structure does not introduce any noticeable trapping. View full abstract»

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  • Recessed 70-nm Gate-Length AlGaN/GaN HEMTs Fabricated Using an \hbox {Al}_{2}\hbox {O}_{3}/\hbox {SiN}_{x} Dielectric Layer

    Publication Year: 2009 , Page(s): 913 - 915
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (235 KB) |  | HTML iconHTML  

    In this letter, a novel process for recessed-gate AlGaN/GaN high-electron-mobility transistors using an Al2O3/SiNx dielectric has been developed. The Al2O3/SiNx dielectric bilayer was used as a recess etch-mask for short-gate-footprint definition. Recessed-gate devices with a gate length of 70 nm have been fabricated on a molecular-beam-epitaxy-grown layer structure using this process. After the removal of the dielectric layers, excellent dc and small-signal results, a high drain-current density of 1.5 A/mm, a unity gain cutoff frequency of 160 GHz, and a maximum frequency of oscillation of 200 GHz were obtained. View full abstract»

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  • Blanket SMT With In Situ N2 Plasma Treatment on the \langle \hbox {100} \rangle Wafer for the Low-Cost Low-Power Technology Application

    Publication Year: 2009 , Page(s): 916 - 918
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (462 KB) |  | HTML iconHTML  

    PMOS degradation with the blanket-stress-memory-technique (SMT) nitride layer on the (100) wafer with ?100? orientation has been observed, and the degradation mechanism is examined. The boron-doping loss from both the PMOS gate and the source/drain region during the SMT process is the root cause. In situ N2 plasma treatment before the SMT layer deposition has been implemented for the first time to recover PMOS performance on the ?100? wafer by reducing the boron-doping loss from the gate and the source/drain region. Reliability like PMOS NBTI has been examined, and no degradation is observed. View full abstract»

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  • Resistive-Switching Characteristics of \hbox {Al}/ \hbox {Pr}_{0.7}\hbox {Ca}_{0.3}\hbox {MnO}_{3} for Nonvolatile Memory Applications

    Publication Year: 2009 , Page(s): 919 - 921
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB) |  | HTML iconHTML  

    A systematic study on the switching mechanism of an Al/ Pr0.7Ca0.3MnO3 (PCMO) device was performed. A polycrystalline PCMO film was deposited using a conventional sputtering method. A thin Al layer was introduced to induce a reaction with the PCMO, forming aluminum oxide (AlOx). Transmission electron microscopy analysis of the interface between Al and PCMO showed that resistive switching was governed by the formation and dissolution of AlOx. Some basic memory characteristics, such as good cycle endurance and data retention of up to 104 s at 125??C, were also obtained. It also showed excellent switching uniformity and high device yield. View full abstract»

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  • Passivation of a (100) Silicon Surface by Silicon Dioxide Grown in Nitric Acid

    Publication Year: 2009 , Page(s): 922 - 924
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (121 KB) |  | HTML iconHTML  

    This letter investigates silicon dioxide layers grown at low temperature in concentrated nitric acid using a two-step process developed by Imai <etal/> for thin-film transistors. With photoconductance measurements, we find that, prior to an anneal, nitric acid oxidation does not passivate the silicon surface, but, after a 30-min nitrogen anneal at 1100degC, a surface recombination velocity (SRV) of 107 cm/s (at Deltan = 1015 cm-3) is attained on 1-Omega ldr cm n-type silicon. The SRV is further decreased to 42 cm/s after a 30-min forming gas anneal (FGA) at 400degC, which is equivalent to a thermal oxide under similar annealing conditions, although it is not stable and returns to its pre-FGA state over time. Capacitance-voltage and photoconductance measurements suggest that the oxides contain a high positive fixed charge-particularly after a 1100degC N2 anneal-which aids the passivation of n-type and intrinsic silicon but harms the passivation of low-resistivity p-type silicon. View full abstract»

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  • The Effect of Oxygen on the Work Function of Tungsten Gate Electrodes in MOS Devices

    Publication Year: 2009 , Page(s): 925 - 927
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (133 KB) |  | HTML iconHTML  

    The effect of oxygen on the work function of tungsten electrodes has been studied. As expected, it was found that the presence of the metastable A15 (??) phase is correlated with oxygen concentration. Tungsten films with minimal oxygen content contain only the stable bcc (??) phase. However, after a forming gas anneal was performed on MOS capacitors made from these films, it was found that the ?? phase converts completely to a strained ?? phase. Despite this uniform transformation, it was found that the work function of the tungsten gate electrodes varies from 4.54-4.91 eV, depending on the partial pressure of oxygen that the tungsten films were grown in. This is a novel work function tuning technique, and it is hypothesized that the observed variation is due solely to the incorporation of oxygen from the growth environment into the W layer at the SiO2/W interface. View full abstract»

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  • Analog BIST Functionality for Microhotplate Temperature Sensors

    Publication Year: 2009 , Page(s): 928 - 930
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (261 KB) |  | HTML iconHTML  

    In this letter, we describe a novel long-term microhotplate temperature-sensor calibration technique suitable for built-in self-test (BIST). The microhotplate thermal resistance (thermal efficiency) and the thermal voltage from an integrated platinum/rhodium thermocouple were calibrated against a polysilicon temperature-sensor calibration curve which drifts over time. Both of these temperature sensors, which cannot be directly calibrated, exhibit excellent long-term temperature stability and are appropriate for BIST functionality. View full abstract»

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  • Novel Thermally Stable Single-Component Organic-Memory Cell Based on Oxotitanium Phthalocyanine Material

    Publication Year: 2009 , Page(s): 931 - 933
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (378 KB) |  | HTML iconHTML  

    This letter reports a novel single-component organic-memory cell based on oxotitanium phthalocyanine (TiOPc) material. The device can achieve good resistive-switching performance such as a high on/off current ratio of about 104, large read signal window (4 V), and good retention (4 h at 1-V read voltage). The organic-memory cell exhibits excellent thermal stability above 525 K due to the thermal robustness of TiOPc, which indicates its potential for hybrid integration with CMOS technology at the back-end process and flexible electronics system. The current-voltage characteristics are comprehensively investigated, and a possible mechanism is proposed and well fitted with the experimental data. The results show that the trap-filling space-charge-limited conduction with TiOPc charge confinement and the electrochemical reaction at the Al/TiOPc interface can elucidate the switching behavior of the memory cell. View full abstract»

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  • Waveguided Ge/Si Avalanche Photodiode With Separate Vertical SEG-Ge Absorption, Lateral Si Charge, and Multiplication Configuration

    Publication Year: 2009 , Page(s): 934 - 936
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB) |  | HTML iconHTML  

    A novel Si-waveguide-integrated Ge/Si avalanche photodiode (APD) is demonstrated for the first time, in which light propagating along the Si waveguide is evanescently absorbed by an overlaying Ge layer selectively grown on it, whereas the avalanche multiplication of photoexcited carriers occurs laterally in the Si-waveguide layer. The APD provides a responsivity of ~7.2 A/W at 1550 nm, which is ~26 times larger than the corresponding vertical Ge/Si p-i-n photodiode, and exhibits a 3-dB bandwidth of ~3.3 GHz, a dark current of ~22 ??A at 22-V bias, and an excess noise factor of ~4, respectively. View full abstract»

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  • Improvement of Electrostatic Discharge Characteristics and Optical Properties of GaN-Based Light-Emitting Diodes

    Publication Year: 2009 , Page(s): 937 - 939
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (387 KB) |  | HTML iconHTML  

    To improve the positive- and negative-voltage electrostatic discharge (ESD) characteristics of GaN light-emitting diodes (LEDs), an air gap was introduced as an ESD protection structure in an Al film on the bottom side of a sapphire substrate. The negative-voltage ESD characteristic of GaN LEDs with an air gap was remarkably improved from -0.3 to -4 kV. The degradation of electroluminescent intensity of GaN LEDs, which was caused by ESD stress, was also suppressed by an air gap in GaN LEDs. An ESD-stress-induced current is believed to flow in an air gap to protect the multiquantum well of GaN LEDs. View full abstract»

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  • Fabrication and Characterization of GaAs Solar Cells on Copper Substrates

    Publication Year: 2009 , Page(s): 940 - 942
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB) |  | HTML iconHTML  

    This letter presents performance comparison between a GaAs/mirror/copper thin-film solar cell and a conventional GaAs solar cell with a thick GaAs substrate. The GaAs thin-film solar cell was fabricated by transferring a GaAs solar cell onto a AuGe/Au mirror-coated copper substrate. With the aid of the excellent copper conductor, the thin-film solar cell exhibits significant improvement in both open-circuit voltage and short-circuit current density. The improved current-voltage (I-V) performance of the thin-film solar cell originates from the following two factors: reduced reverse saturation current by good heat dissipation of copper and enhanced light absorption by the highly reflective AuGe/Au mirror. The role of the mirror can further be verified in the measurement of external quantum efficiency (EQE) response where the thin-film solar cell exhibits a larger EQE response in the wavelength range of 700-900 nm than the conventional GaAs solar cell with the same active absorbing thickness. View full abstract»

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  • Photosensitive Inverter and Ring Oscillator With Pseudodepletion Mode Load for LCD Applications

    Publication Year: 2009 , Page(s): 943 - 945
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (387 KB) |  | HTML iconHTML  

    Photosensitive inverters and ring oscillators (ROs) with pseudodepletion mode loads (PDMLs) were integrated in LCD panels using conventional mass production processes. The delay time (t pd) of five-stage ROs with PDML reduced from 204.3 ??s under dark to 16.3 ??s under backlight illumination of 20 000 lx. The oscillation frequency exhibited a power-law dependence (f osc ??IL??) on the backlight illuminance with the extracted fitting parameter ?? = 0.447 at room temperature. View full abstract»

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  • High-Frequency ZnO Thin-Film Transistors on Si Substrates

    Publication Year: 2009 , Page(s): 946 - 948
    Cited by:  Papers (18)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (398 KB) |  | HTML iconHTML  

    Record microwave frequency performance was achieved with nanocrystalline ZnO thin-film transistors fabricated on Si substrates. Devices with 1.2-mum gate lengths and Au-based gate metals had current and power gain cutoff frequencies of fT = 2.45 GHz and fmax = 7.45 GHz, respectively. Same devices had drain-current on/off ratios of 5 times1010 exhibited no hysteresis effects and could be operated at a current density of 348 mA/mm. The microwave performances of devices with 1.2- and 2.1- mum gate lengths and 50- and 100-mum gate widths were compared. View full abstract»

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  • Schottky Barrier Height of Erbium Silicide on  \hbox {Si}_{1 - x}\hbox {C}_{x}

    Publication Year: 2009 , Page(s): 949 - 951
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    In this letter, the Schottky barrier height of erbium silicide contacts formed on Si1-xCx alloys was measured. The alloys were pseudomorphically grown on Si wafers with 0% to 1.2% C occupying the substitutional sites. Schottky barrier diodes were fabricated with an ideality factor of 1.13 or less. The hole barrier height was found to be 0.73 eV independent of the C concentration. This suggests that the electron barrier height should decrease with increasing C concentration due to the reduction in the semiconductor bandgap. For 1.2% C, the electron barrier is estimated to be 0.29 eV. View full abstract»

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  • High-Gain SiC MESFETs Using Source-Connected Field Plates

    Publication Year: 2009 , Page(s): 952 - 953
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (150 KB) |  | HTML iconHTML  

    We demonstrate for the first time improvement of radio-frequency (RF) gain of SiC MESFETs by using source-connected field plates (FPs). MESFETs fabricated with this approach show a new record maximum stable gain exceeding 15.7 dB at 3.1 GHz. This is 2.7 dB higher than the baseline devices without FP. RF power output greater than 4 W/mm was also achieved showing the potential of these devices for high-power operation. View full abstract»

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  • MILC-TFT With High- \kappa Dielectrics for One-Time-Programmable Memory Application

    Publication Year: 2009 , Page(s): 954 - 956
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (351 KB) |  | HTML iconHTML  

    In this letter, for the first time, one-time-programmable (OTP) memory fabricated on the low-temperature poly-Si p-channel thin-film transistor (TFT) with metal-induced lateral-crystallization channel layer and high-kappa dielectrics is demonstrated. The state of this OTP memory can be identified by the scheme of gate-induced drain leakage current measurement. The OTP-TFT memory has good electrical characteristics in terms of low threshold voltage Vth ~ -0.78 V, excellent subthreshold swing ~ 105 mV/dec, low operation voltage, faster programming speeds, and excellent reliability characteristics. View full abstract»

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  • 3510-V 390- \hbox {m}\Omega \cdot\hbox {cm}^{2} 4H-SiC Lateral JFET on a Semi-Insulating Substrate

    Publication Year: 2009 , Page(s): 957 - 959
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB) |  | HTML iconHTML  

    The performance of high-voltage 4H-SiC lateral JFETs on a semi-insulating substrate is reported in this letter. The design of the voltage-supporting layers is based on the charge compensation of p- and n-type epilayers. The best measured breakdown voltage is 3510 V, which, to the authors' knowledge, is the highest value ever reported for SiC lateral switching devices. The Ron of this device is 390 m????cm2, in which 61% is due to the drift-region resistance. The BV2/Ron is 32 MW/cm2, which is typical among other reported SiC lateral devices. View full abstract»

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  • Increase in Reverse Operation Limit by Barrier Height Control of Diamond Schottky Barrier Diode

    Publication Year: 2009 , Page(s): 960 - 962
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB) |  | HTML iconHTML  

    Diamond is a promising material for high-power and low-loss semiconductor devices. However, the reported reverse blocking electric field of diamond-based power devices is as low as 2 MV/cm, and their performance is worse than ideal. We have developed reach-through-type Schottky barrier diodes (SBDs) with various Schottky barrier heights (SBHs) by changing metals. SBDs with high SBH show low leakage current and high operation limit of 3.1 MV/cm. This indicates that the reverse operation limit of diamond SBDs is determined not by leakage through defects but by carrier transport through the barrier. Reduction of specific on-resistance increases Baliga's figure of merit to 51 MW/cm2, which is tenfold higher than the Si limit. View full abstract»

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IEEE Electron Device Letters publishes original and significant contributions relating to the theory, modeling, design, performance and reliability of electron devices.

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Amitava Chatterjee