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Breakdown Voltage (breakdown + voltage)
Selected AbstractsStochastic and Relaxation Processes in Argon by Measurements of Dynamic Breakdown VoltagesCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7 2005V. Lj. Abstract Statistically based measurements of breakdown voltages Ub and breakdown delay times td and their variations in transient regimes of establishment and relaxation of discharges are a convenient method to study stochastic processes of electrical breakdown of gases, as well as relaxation kinetics in afterglow. In this paper the measurements and statistical analysis of the dynamic breakdown voltages Ub for linearly rising (ramp) pulses in argon at 1.33 mbar and the rates of voltage rise k up to 800 V s,1 are presented. It was found that electrical breakdowns by linearly rising (ramp) pulses is an inhomogeneous Poisson process caused by primary and secondary ionization coefficients , , , and electron yield Y variations on the voltage (time). The experimental breakdown voltage distributions were fitted by theoretical distributions by applying approximate analytical and numerical models. The afterglow kinetics in argon was studied based on the dependence of the initial electron yield on the relaxation time Y0 (, ) derived from fitting of distributions. The space charge decay was explained by the surface recombination of nitrogen atoms present as impurities. The afterglow kinetics and the surface recombination coefficients on the gas tube and cathode were determined from a gas-phase model. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The role of setback layers on the breakdown characteristics of AlGaAs/GaAs/GaN HBTsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008Chuanxin Lian Abstract Breakdown voltages (VCBO) of AlGaAs/GaAs/GaAs and AlGaAs/GaAs/GaAs-setback/GaN HBTs have been compared both theoretically and experimentally with respect to setback layer thicknesses and the doping type. VCBO was calculated using a non-local energy model. The hard breakdown voltage was measured on as-grown GaAs homojunctions and AlGaAs/GaAs/GaN HBTs formed by direct wafer fusion. The calculation showed an increase of VCBO from , 20 V to , 325 V by replacing the GaAs collector with GaN, and VCBO ,90 V was indeed measured. The smaller than predicted VCBO is attributed to the large leakage current currently present in the fused junctions. Insertion of a lightly doped GaAs setback layer has resulted in improved current gain of the fused HBTs, but it also degrades the breakdown characteristics. 20-30 nm setback layers were found to maintain VCBO significantly higher than that of GaAs homojunctions and likely reasonable current gains. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Novel modelling of residual operating time of transformer oilEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 4 2003M. A. A. Wahab This paper presents techniques developed to accurately model the characteristics of transformer oil for the purpose of predicting the effect of aging on these characteristics. Aging causes some of the transformer oil characteristics to violate the internationally specified limits. The purpose of this simulation is to develop alternative techniques to predict the operating time after which these characteristics would violate the limits. The results obtained from monitoring of twenty in-service power transformers for long period of operating time up to ten years have been implemented in developing the proposed models. The physical, chemical and electrical characteristics have been determined periodically by internationally specified testing methods. The patterns of violation sequence of the standard limits, against operating time, by different transformer oil characteristics have been revealed and the most common pattern has been determined. The definition of residual operating time (trot) of the different transformer oil characteristics has been introduced. The choice of transformer oil breakdown voltage trot to represent that of the transformer oil characteristics has been justified. Modelling of trot as a function of transformer oil breakdown voltage, total acidity and water content by multiple-linear regression has been proposed and verified. Also, polynomial regression model of trot as a function only of transformer oil breakdown voltage has been given. The accuracy and applicability of these models and the different modelling techniques have been discussed and proved. [source] The role of methylnaphthalene in EHV cable oil as related to oil breakdown and discharge velocityEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 6 2002A. Al-Sulaiman This experimental investigation explores the effect of high voltage lightning surges on the insulating oil used in the oil filled extra high voltage cables that serve electric power networks worldwide. Using non-uniform electrode configuration, the breakdown voltage and corresponding discharge propagation velocities in oil samples that are doped with trace amounts of 1-Methylnaphthalene are investigated under both polarities of applied stresses in gap spacing of up to 10 mm. Two distinct ranges of additive concentrations are observed which effect these characteristics. Generally, the positive discharge growth decreases with increase in gap spacing while the negative ones show opposite behaviour. Anomalous behaviour of discharge growth is observed at an optimum concentration of additive, as it attains supersonic velocity which increases with the increase in gap spacing. A correlation between the positive impulse breakdown voltage and the discharge propagation velocity is also established. [source] Microstructure,Property Relationships for Low-Voltage VaristorsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2010Wen-Hsuan Pan The low-voltage varistors with various layer thickness are prepared by laminating thin ZnO-based ceramic layers and AgPd electrodes together. The breakdown voltage dose not exhibit linear relationship with layer thickness. It is due to that the presence of the AgPd electrodes enhances the growth of ZnO grains. As some ZnO grains are large enough to touch the upper and lower electrodes, the breakdown voltage of the varistor is only 3.7 V. The nonlinear coefficient of the low-voltage varistor is 33. Such nonlinear current,voltage behavior is mainly contributed by the interface between the AgPd electrode and ZnO grains. [source] Electrodeposition of Titania Thin Films on Metallic Surface for High- k Dielectric ApplicationsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2010Biplab K. Roy Current microelectronics devices based on flexible as well as rigid substrates demand high dielectric constant (k) films to be grown on conductive substrate from a low-cost, low-temperature deposition technique. In this study, we produced high- k titania (TiO2) films through an affordable electrodeposition protocol from the electrochemical bath maintained at about 0°C. The deposition occurs through a rapid hydrolysis mechanism of titanium containing ions in the precursor solution aided by electrochemically generated hydroxyl ions formed near the cathode surface (copper (Cu) substrate). Upon attaining a sufficient supersaturation level, such hydrolyzed species precipitate to form a titania thin film on the cathode surface. While depositing from a highly acidic precursor solution, Cu substrate was protected by a cathodic potential (,3 to ,5 V against the counter electrode). The resultant titania films show nanoparticulate structures evolved from nucleation and growth events of the in situ precipitated particles. Much higher deposition rate (about 1 ,m/min) was observed compared with that of typical chemical bath deposition. The resultant films with a thickness of 1500 nm grown on Cu exhibit very high dielectric properties (e.g., k,30, capacitance density >110 nF/in.2 at 100 kHz) and moderate breakdown voltage (VB) (,17.5 V). These properties indicate the potential of electrodeposited titania films to be used as a small-area thin-film capacitor for miniaturized electronic devices. [source] Effects of Calcination Temperature and A/B Ratio on the Dielectric Properties of (Ba,Ca)(Ti,Zr,Mn)O3 for Multilayer Ceramic Capacitors with Nickel ElectrodesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2000Wen-Hsi Lee The electrical performance of multilayer ceramic capacitors (MLCCs) with Ni inner electrodes, made from (Ba,Ca)(Ti,Zr,Mn)O3 (BCTZM), is closely related to the calcination temperature and the A/B ratio of the powder. For materials showing A/B = 1.000, the lifetime, the breakdown voltage, and the RC increase with higher calcination temperatures. No significant effect of the calcination temperature on RC and lifetime was found for materials showing A/B = 0.991. The isoelectric point of BCTZM is shifted toward higher pH values when the calcination temperature is decreased. The above results are attributed to the colloidal stability of aqueous BCTZM suspensions and the resulting green density of powder compacts. [source] Correlation of pre-breakdown sites and bulk defects in multicrystalline silicon solar cellsPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 2-3 2009Dominik Lausch Abstract Strong correlation between the pre-breakdown sites visible in dark lock-in thermography due to local heating and the intensity of spatially resolved electroluminescence of reverse-biased solar cells was observed. By comparing differently texturised solar cells we could show that the pre-breakdown sites are not correlated to the surface morphology, e.g. etch pits resulting in local field enhancement. The positions of the pre-breakdown sites are identical for acidic and alkaline texturised solar cells and therefore are directly related to bulk defects in the wafer. Nevertheless, the breakdown voltage is lower for acidic texturised solar cells; the parameters of breakdown are influenced by the texture in contrast to the position. Also pre-breakdown sites are observed in areas without specific surface features for alkaline texturised solar cells. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Design, process, and performance of all-epitaxial normally-off SiC JFETsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2009Rajesh K. Malhan Abstract This paper reviews the normally-off (N - off) and normally-on (N - on) SiC junction field effect transistor (JFET) concepts and presents an innovative all-epitaxial double-gate trench JFET (DGTJFET) structure. The DGTJFET design combines the advantages of lateral and buried gate JFET concepts. The lateral JFET advantage is the epitaxial definition of the channel width and the buried gate JFET advantage is the small cell size. In the DGTJFET process the epitaxial embedded growth in trenches facilitates the small cell pitch and the vertical direction of the channel. A detailed numerical simulation analysis compares the potential of the DGTJFET design with reported lateral channel and buried gate JFET structures. Migration enhanced embedded epitaxy (ME3) and planarization processes were developed to realize narrow cell pitch DGTJFETs for high-density power integration. The highly doped vertical channel of the DGTJFET defined by the ME3 growth process makes it possible to accurately control the sub-micron channel dimensions in order to realize a low specific on-state resistance (RON) and a high saturation current capability. The anisotropic nature of SiC is taken into account for the channel design considerations. The successful application of the new process technologies for the development of the all-epitaxial DGTJFETs is discussed. Fabricated 5.5 ,m cell pitch 4H-SiC DGTJFETs demonstrate the saturation current density capability of more than 1000 A/cm2. N - off and N - on DGTJFETs with 2.25 mm squared chip size and 9.5 ,m cell pitch output 15 A and 20 A at gate voltage of 2.5 V and drain voltage of 5.0 V. The specific RON of the N - off and N - on DGTJFETs is at room temperature 8.1 m , cm2 and 6.3 m, cm2, respectively, indicating that N - off devices can be realized at the expense of a slight increase in specific RON of approximately 25%. DGTJFETs with a 13 ,m drift layer doped to 5.0 × 1015 cm,3 are demonstrated with a breakdown voltage in the range of 1200 V to 1550 V at the wafer level with a leakage current below 10 ,A. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Over 55 A, 800 V high power AlGaN/GaN HFETs for power switching applicationPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007Nariaki Ikeda Abstract We developed new ohmic electrodes combined with an Al-silicide and a molybdenum for AlGaN/GaN HFETs to realize a high power switching application. As a result, the maximum drain current of the HFET was over 55 A and the breakdown voltage was about 800 V. The specific on-state resistance of the HFET was smaller than that of a Si Cool MOSFET. Furthermore, we examined the dynamic characteristics. The turn-off and turn-on delay time were 14.8 nsec. and 8.4 nsec. at the condition of 100 V, respectively. These values were considerbly smaller compared with those of Si Cool MOSFETs. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Control of GaAs-MESFET breakdown voltage by Shannon implantationPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2007Y. Kumar Abstract The dependence of GaAs-MESFET gate-drain breakdown voltage on gate-Schottky barrier enhancement by Shannon-implantation is analyzed. The analytical results show that the breakdown voltage can be increased by increasing the Shannon-implant dose. However, the tolerable limit of hole accumulation under the gate does not allow the breakdown voltage to be increased beyond a certain limit. The breakdown voltage limit is higher for a channel of lighter doping. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of insulating barrier thickness on the magnetoresistance properties of a magnetic tunnel junction with Zr-alloyed Al oxide barrierPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2004Chul-Min Choi Abstract We have investigated the magnetoresistive properties and thermal and electrical stability of a magnetic tunnel junction (MTJ) with a high-quality, ultra-thin Zr-alloyed Al oxide (ZrAl oxide) barrier of below 1.0 nm. We obtained the highest bias voltage and breakdown voltage of 711 mV and 1.75 V for a 1.6-nm-thick barrier. The resistance drops from 1850 , to 72 , as the ZrAl thickness decreases from 1.6 to 0.6 nm, respectively. A significant TMR (Tunneling Magneto-resistance) value of 17% and a junction resistance of 98 , were obtained for a MTJ with a ZrAl oxide barrier thickness of 0.8 nm. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High power AlGaN/GaN HFETs on 4 inch Si substratesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009Nariaki Ikeda Abstract In this paper, we successfully demonstrate an AlGaN/GaN HFET with a high breakdown voltage on 4-inch Si substrates. In order to obtain the high breakdown voltage and to improve the crystalline quality of GaN layers, a thick GaN epitaxial layer including a buffer layer was grown. The breakdown voltage and the maximum drain current were achieved to be over 1.3 kV and 120 A, respectively. Furthermore, the suppression of a current collapse phenomenon was examined. The on-resistance was not significantly increased up to a high drain off-bias-stress of 900 V. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High drain current and low on resistance normally-off-mode AlGaN/GaN junction HFETs with a p-type GaN gate contactPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008T. Fujii Abstract The normally-off-mode junction HFETs with a p-type GaN gate contact showing high drain current and an extremely large on/off ratio were successfully fabricated by MOVPE. The drain currents were found to be very sensitive to the surface of the u-AlGaN barrier exposed by RIE etching. A reproducible and stable high drain current was achieved using a very thin SiN passivation layer. The maximum drain current was 1.58×10,1 A/mm at VGS = 4 V, while the drain current at VGS = 0 V was as low as 1.45×10,8 A/mm. Therefore, an on/off ratio of 107 has been achieved. The sub-threshold swing was as small as 90 mV/dec.. The on resistance was 3.4 m,cm2, the threshold voltage was +0.45 V, and the breakdown voltage was over 325 V. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Laterally engineered field-plate GaN HEMTs for millimeter-wave applicationsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008K. S. Boutros Abstract A laterally Engineered Field Plate (EFP) design is implemented to obtain a field-plated, 30 nm gate structure with a small added capacitance due to the presence of the field plate. By reducing the field plate length, and simultaneously placing it away from the gate, we are able to reduce the field plate capacitance while maintaining its effectiveness in reducing the peak electric field at the gate edge. GaN HEMT EFP devices were fabricated with 30 nm gate lengths, and 70nm field plates. A three-terminal breakdown voltage (VBD) of 63 V was measured for the 30 nm EFP device. This VBD represents a 2x improvement over the breakdown of 100nm conventional T-gate devices fabricated on the same wafer. The device had an extrinsic FT of 65 GHz and an FMAX of 120 GHz. Improvement in both Pout and PAE was also realized with this new gate design compared to conventional T-gate devices. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Buffer breakdown voltage of AlGaN/GaN HFET on a 4 inch Si(111) substrate grown by MOCVDPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007Masayuki Iwami Abstract The buffer breakdown voltage and the electron mobility in a two dimensional gas (2DEG) of AlGaN/GaN HFETs on 4 inch Si(111) substrates grown by metalorganic chemical vapor deposition was investigated. The relationship between the electrical properties of HFETs and the crystalline quality of the GaN layer are studied by X-ray diffraction and photoluminescence measurements. The buffer breakdown voltage decreases with an increase in the FWHM of the X-ray (0002) diffraction peak. The electron mobility in a 2DEG decreases with an increase in FWHM of the X-ray (102) diffraction peak. These results indicate that a screw component of the threading dislocations in the GaN layer is a primary source for buffer leakage, and that edge dislocations in the GaN layer have a scattering effect on the 2DEG transport. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Low on-resistance of GaN p-i-n vertical conducting diodes grown on 4H-SiC substratesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007Atsushi Nishikawa Abstract We investigated the resistance of conductive AlGaN buffer layers and the current-voltage characteristics of GaN p-i-n vertical conducting diodes on n -type 4H-SiC substrates grown by low-pressure metalorganic vapor-phase epitaxy. High Si doping of the AlGaN buffer layer at the AlGaN/SiC interface produces ohmic current-voltage characteristics in spite of the large band offset between AlGaN and 4H-SiC. Owing to the optimization of the AlGaN buffer layer, a low on-resistance (Ron) of 1.12 m, cm2 with high breakdown voltage (VB) of 300 V is obtained for a GaN p-i-n vertical conducting diode on a 4H-SiC substrate, leading to the figure of merit (VB2/Ron) of 80 MW/cm2, which is larger than that for the diode with the same structure on a 6H-SiC substrate (62 MW/cm2). This result indicates that 4H-SiC is preferable for fabricating GaN-based electronic devices with a low on-resistance and high breakdown voltage. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Dynamic drift-diffusion simulation of InP/InGaAs SAGCM APDPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2007Y. G. Xiao Abstract In this work, based on the advanced drift and diffusion model with commercial software, the Crosslight APSYS, InP/InGaAs separate absorption, grading, charge and multiplication APDs for high bit-rate operation have been modeled. Basic physical quantities such as band diagram, optical absorption and generation are calculated. Performance characteristics such as dark- and photo-current, photoresponsivity, multiplication gain, breakdown voltage, excess noise, frequency response and bandwidth etc., are simulated. The modeling results are selectively presented, analyzed, and some results are compared with experiments. Device design optimization issues are further discussed with respect to the applicable features of the Crosslight APSYS within the framework of the drift-diffusion theory. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Dual-gate AlGaN/GaN high-electron-mobility transistors with short gate length for high-power mixersPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2006K. Shiojima Abstract We have fabricated dual-gate AlGaN/GaN high-electron-mobility transistors (HEMTs) with a short gate on SiC substrates for use in high-power mixers and have measured the DC and up-conversion RF characteristics. A device with a T-shaped gate (0.15 µm × 300 µm) exhibits a maximum transconductance of 40 mS, an on-state breakdown voltage of over 30 V, and off-state breakdown voltage of 86 V. The maximum RF output power (PRFout) is 17 dBm, and the up-conversion gain is 7.5 dB at a frequency of 10 GHz when the bias point voltage is 30 V. As the local frequency increases from 2 to 10 GHz, PRFout and the gain decrease by only 2 and 2.6 dB, respectively. Shortening the gate was found to be effective in improving the frequency characteristics of a mixer at frequencies up to and including the X-band. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] AlGaN/GaN dual-gate high electron mobility transistors on SiC substrates for high-power mixersPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2005K. Shiojima Abstract We have demonstrated dual-gate AlGaN/GaN high-electron-mobility transistors on SiC substrates for high-power mixers and examined DC and up-conversion RF measurements with drain-source bias voltages (VDS) to analyze the possible output level. The 0.7 × 300 µm-gate device exhibited the maximum transconductance of 47 mS, maximum RF power of 19.6 dBm and up-conversion gain of 11 dB at 2 GHz when VDS = 15 V. For VDS of over 15 V, the devices occasionally broke down, because, although the device can handle more drain current, but the voltage swing reached the breakdown voltage of about 30 V. These results indicate that a Watt-class output mixer can be easily achieved with this simple dual-gate structure. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] 4H SiC Epitaxial Growth with Chlorine AdditionCHEMICAL VAPOR DEPOSITION, Issue 8-9 2006F. La Abstract The growth rate of a 4H-SiC epitaxial layer has been increased by a factor of 19 (up to 112,,m h,1) with respect to the standard process, with the introduction of HCl in the deposition chamber. The epitaxial layers grown with the addition of HCl has been characterized by electrical, optical, and structural characterization methods. The effects of various deposition parameters on the epitaxial growth process have been described, and an explanation of this behavior in terms of the diffusion coefficient on the surface, Ds, and the ratio between the characteristic times, ,D:,G, has been provided. The diodes, manufactured on the epitaxial layer grown with the addition of HCl at 1600,°C, have electrical characteristics comparable with the standard epitaxial process. This process is very promising for high-power devices with a breakdown voltage of 10,kV. [source] Strain-engineered novel III,N electronic devices with high quality dielectric/semiconductor interfacesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003M. Asif Khan Abstract Since the early demonstration of 2D-electron gas [M. A. Khan et al., Appl. Phys. Lett. 60, 3027 (1992)] and a heterojunction field effect transistor (HFET) [M. Asif Khan et al., Appl. Phys. Lett. 63, 1214 (1993)] in III,N materials, rapid progress has been made to improve the DC and RF performance of GaN,AlGaN based HFETs. Stable and impressive microwave powers as high as 4,8 W/mm have been reported for device operation frequencies from 10 to 35 GHz. The key reason for these high performance numbers is an extremely large sheet carrier densities (>1 × 1013 cm,2) that can be induced at the interfaces in III,N hetereojunction [A. Bykhovsk et al., J. Appl. Phys. 74, 6734 (1993); M. Asif Khan et al., Appl. Phys. Lett. 75, 2806 (1999)]. These are instrumental in screening the channel dislocations thereby retaining large room temperature carrier mobilities (>1500 cm2/Vs) and sheet resistance as low as 300 ,/sq. These numbers and the high breakdown voltages of the large bandgap III,N material system thus enable rf-power approximately 5,10 times of that possible with GaAs and other competitor's technologies. We have recently introduced a unique pulsed atomic layer epitaxy approach to deposit AlN buffer layers and AlN/AlGaN superlattices [J. Zhang et al., Appl. Phys. Lett. 79, 925 (2001); J. P. Zhang et al., Appl. Phys. Lett. 80, 3542 (2002)] to manage strain and decrease the dislocation densities in high Al-content III,N layers. This has enabled us to significantly improve GaN/AlGaN hetereojunctions and the device isolation. The resulting low defect layers are not only key to improving the electronic but also deep ultraviolet light-emitting diode devices. For deep UV LED's they enabled us to obtain peak optical powers as high as 10 mW and 3 mW for wavelengths as short as 320 nm and 278 nm. Building on our past work [M. Asif Khan et al., Appl. Phys. Lett. 77, 1339 (2000); X. Hu et al., Appl. Phys. Lett. 79, 2832 (2001)] we have now deposited high quality SiO2/Si3N4 films over AlGaN with low interface state densities. They have then been used to demonstrate III,N insulating gate transistors (MOSHFET (SiO2) and MISHFET (Si3N4) with gate leakage currents 4,6 order less than those for conventional GaN,AlGaN HFETs. The introduction of the thin insulator layers (less then 100 Å) under the gate increases the threshold voltage by 2,3 V. In addition, it reduces the peak transconductance gm. However the unity cut-off frequency, the gain and the rf-powers remain unaffected as the gm/Cgs (gate-source capacitance) ratio remains unchanged. In addition to managing the defects and gate leakage currents we have also employed InGaN channel double heterojunction structures (AlInGaN,InGaN,GaN) to confine the carriers thereby reducing the spillover into trappings states. These InGaN based MOS-DHFETs exhibited no current-collapse, extremely low gate leakage currents (<10,10 A/mm) and 10,26 GHz rf-powers in excess of 6 W/mm. We have also demonstrated the scalability and stable operation of our new and innovative InGaN based insulating gate heterojunction field effect transistor approach. In this paper we will review the III,N heterojunction field-effect transistors progress and pioneering innovations including the excellent work from several research groups around the world. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Off-state breakdown in InAlN/AlN/GaN high electron mobility transistorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009J. Kuzmik Abstract Unpassivated InAlN/AlN/GaN high electron mobility transistors off-state breakdown is analyzed for different gate-to-drain distances. The breakdown voltage linearly increases with the gate to drain distance reaching 350 V for a 10 ,m contact separation; the sub-threshold leakage current is < 10,5 A/mm. Similar breakdown voltages and leakage current are obtained on GaN buffer for two Ohmic contacts if their distance is the same. It is suggested that the breakdown is governed by injection/avalanche processes in the GaN buffer layer and is basically not affected by InAlN barrier. Our conclusions are further supported by measuring all currents in the three-terminal configuration of the transistors before and during the breakdown and by using a drain current injection technique. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fabrication of enhancement-mode AlxGa1,xN/GaN junction heterostructure field-effect transistors with p-type GaN gate contactPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007T. Fujii Abstract We have investigated the device performance, such as the breakdown voltages between gate-source contacts and drain-source contacts, threshold voltage (Vth) and on resistance (RON), of enhancement-mode AlxGa1,xN/GaN junction heterostructure field-effect transistors (JHFET) with a p-type GaN gate. Fabricating an Al0.15Ga0.85N/GaN JHFET with a gate length of 2 ,m without surface passivation, we have achieved a completely enhancement-mode JHFET with a threshold voltage of +0.55 V, and breakdown voltages between gate-source and drain-source were over 100 V and 250 V, respectively. RON is as low as 4.5 m, · cm2 at VG = 3.0 V. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||