共查询到20条相似文献,搜索用时 15 毫秒
1.
Domeij M. Lee H.-S. Danielsson E. Zetterling C.-M. Ostling M. Schoner A. 《Electron Device Letters, IEEE》2005,26(10):743-745
This paper reports the fabrication of epitaxial 4H-SiC bipolar junction transistors (BJTs) with a maximum current gain /spl beta/=64 and a breakdown voltage of 1100 V. The high /spl beta/ value is attributed to high material quality obtained after a continuous epitaxial growth of the base-emitter junction. The BJTs show a clear emitter-size effect indicating that surface recombination has a significant influence on /spl beta/. A minimum distance of 2-3 /spl mu/m between the emitter edge and base contact implant was found adequate to avoid a substantial /spl beta/ reduction. 相似文献
2.
Krishnaswami S. Agarwal A. Sei-Hyung Ryu Capell C. Richmond J. Palmour J. Balachandran S. Chow T.P. Bayne S. Geil B. Jones K. Scozzie C. 《Electron Device Letters, IEEE》2005,26(3):175-177
This paper presents the development of 1000 V, 30A bipolar junction transistor (BJT) with high dc current gain in 4H-SiC. BJT devices with an active area of 3/spl times/3 mm/sup 2/ showed a forward on-current of 30 A, which corresponds to a current density of 333 A/cm/sup 2/, at a forward voltage drop of 2 V. A common-emitter current gain of 40, along with a low specific on-resistance of 6.0m/spl Omega//spl middot/cm/sup 2/ was observed at room temperature. These results show significant improvement over state-of-the-art. High temperature current-voltage characteristics were also performed on the large-area bipolar junction transistor device. A collector current of 10A is observed at V/sub CE/=2 V and I/sub B/=600 mA at 225/spl deg/C. The on-resistance increases to 22.5 m/spl Omega//spl middot/cm/sup 2/ at higher temperatures, while the dc current gain decreases to 30 at 275/spl deg/C. A sharp avalanche behavior was observed at a collector voltage of 1000 V. Inductive switching measurements at room temperature with a power supply voltage of 500 V show fast switching with a turn-off time of about 60 ns and a turn-on time of 32 ns, which is a result of the low resistance in the base. 相似文献
3.
Jianhui Zhang Luo Y. Alexandrov P. Fursin L. Zhao J.H. 《Electron Device Letters, IEEE》2003,24(5):327-329
This work reports the development of high power 4H-SiC bipolar junction transistors (BJTs) by using reduced implantation dose for p+ base contact region and annealing in nitric oxide of base-to-emitter junction passivation oxide for 2 hours at 1150/spl deg/C. The transistor blocks larger than 480 V and conducts 2.1 A (J/sub c/=239 A/cm/sup 2/) at V/sub ce/=3.4 V, corresponding to a specific on-resistance (R/sub sp on/) of 14 m/spl Omega/cm/sup 2/, based on a drift layer design of 12 /spl mu/m doped to 6/spl times/10/sup 15/cm/sup -3/. Current gain /spl beta//spl ges/35 has been achieved for collector current densities ranging from J/sub c/=40 A/cm/sup 2/ to 239 A/cm/sup 2/ (I/sub c/=2.1 A) with a peak current gain of 38 at J/sub c/=114 A/cm/sup 2/. 相似文献
4.
E. D. Luckowski J. M. Delucca J. R. Williams S. E. Mohney M. J. Bozack T. Isaacs-Smith J. Crofton 《Journal of Electronic Materials》1998,27(4):330-334
Results are reported for ohmic contacts formed on n-type 4H and 6H-SiC using nichrome (80/20 weight percent Ni/Cr). The electrical
characteristics of these NiCr contacts are similar to those of contacts formed on 6H-SiC using pure Ni (∼1×10−5Ω-cm2 for moderately doped material), but the contacts exhibit significant improvement with regard to physical stability. Composite
Au/NiCr contacts exhibit good stability during long-term anneals (∼2500 h) at 300°C without the requirement of a diffusion
barrier layer between the NiCr ohmic contact layer and the Au cap layer. In addition, the use of NiCr results in success rates
near 100% for direct wire bonding to the Au cap layers. Characterization of the contacts by Auger electron spectroscopy, Rutherford
backscattering spectroscopy, and transmission electron microscopy provides an explanation for the observed behavior. 相似文献
5.
Huili Xing Chavarkar P.M. Keller S. DenBaars S.P. Mishra U.K. 《Electron Device Letters, IEEE》2003,24(3):141-143
N-p-n Al/sub 0.05/GaN/GaN heterojunction bipolar transistors with a common emitter operation voltage higher than 330 V have been demonstrated using selectively regrown emitters. Devices were grown by metalorganic chemical vapor deposition on sapphire substrates. The n-type emitter was grown selectively on a 100-nm-thick p-base with an 8 /spl mu/m n-collector structure using a dielectric mask. The shallow etch down to the collector mitigates damages induced in the dry etch, resulting a low leakage and a high breakdown. The graded AlGaN emitter results in a common emitter current gain of /spl sim/18 at an average collector current density of up to 1 kA/cm/sup 2/ at room temperature. 相似文献
6.
X. Niu 《International Journal of Electronics》2013,100(4):531-542
Considering the circumstance of heterogeneous voice flows, first, by applying Markov chain, this paper proposes an unsaturated analytical model for the IEEE 802.11e EDCA protocol, which considers the condition of non-ideal transmission channel and the character of the occurrence of backoff countdown at the beginning of time slot in EDCA protocol. Furthermore, according to the proposed model, the media access delay and throughput of a flow are analysed, and the flow-oriented call admission control (CAC) scheme is proposed. Finally, the simulation results are shown to confirm that the proposed CAC scheme can guarantee the requirements of throughput and delay of voice flows, and can admit more voice flows to improve the utilisation efficiency of network resources by choosing the appropriate values of the minimum contention window or the appropriate varieties of voice flows. 相似文献
7.
The Ni/Ti/Ni multilayer ohmic contact properties on a 4H-SiC substrate and improved adhesion with the Ti/Au overlayer have been investigated. The best specific contact resistivity of 3.16 × 10^-5 Ω.cm^2 was obtained at 1050 ℃. Compared with Ni/SiC ohmic contact, the adhesion between Ni/Ti/Ni/SiC and the Ti/Au overlayer was greatly improved and the physical mechanism under this behavior was analyzed by using Raman spectroscopy and X-ray energy dispersive spectroscopy (EDS) measurement. It is shown that a Ti-carbide and Ni-silicide compound exist at the surface and there is no graphitic carbon at the surface of the Ni/Ti/Ni structure by Raman spectroscopy, while a large amount of graphitic carbon appears at the surface of the Ni/SiC structure, which results in its bad adhesion. Moreover, the interface of the Ni/Ti/Ni/SiC is improved compared to the interface of Ni/SiC. 相似文献
8.
Byung-Teak Lee Jong-Yoon Shin Seon-Hoon Kim Jin-Hyeok Kim Sang-Yoon Han Jong Lam Lee 《Journal of Electronic Materials》2003,32(6):501-504
Interfacial reactions, surface morphology, and current-voltage (I-V) characteristics of Ti/Al/4H-SiC and TiN/Al/4H-SiC were
studied before and after high-temperature annealing. It was observed that surface smoothness of the samples was not significantly
affected by the heat treatment at up to 900°C, in contrast to the case of Al/SiC. Transmission electron microscopy (TEM) observation
of the Ti(TiN)/Al/SiC interface showed that Al layer reacted with the SiC substrate at 900°C and formed an Al-Si-(Ti)-C compound
at the metal/SiC interface, which is similar to the case of the Al/SiC interface. The I-V measurement showed reasonable ohmic
properties for the Ti/Al films, indicating that the films can be used to stabilize the Al/SiC contact by protecting the Al
layer from the potential oxidation and evaporation problem, while maintaining proper contact properties. 相似文献
9.
S. Tsukimoto T. Sakai T. Onishi Kazuhiro Ito Masanori Murakami 《Journal of Electronic Materials》2005,34(10):1310-1312
Fabrication procedures for silicon carbide power metal oxide semiconductor field effect transistors (MOSFETs) can be improved
through simultaneous formation (i.e., same contact materials and one step annealing) of ohmic contacts on both the p-well
and n-source regions. We have succeeded with the simultaneous formation of the ohmic contacts for p- and n-type SiC semiconductors
by examining ternary Ni/Ti/Al materials with various compositions, where a slash symbol “/” indicates the deposition sequence
starting with Ni. The Ni(20 nm)/Ti(50 nm)/Al(50 nm) combination provided specific contact resistances of 2 × 10−3 Ω-cm2 and 2 × 10−4 Ω-cm2 for p- and n-type SiC, respectively, after annealing at 800°C for 30 min, where the doping level of Al in the SiC substrate
was 4.5 × 1018 cm−3 and the level of N was 1.0 × 1019 cm−3. 相似文献
10.
《Solid-state electronics》2006,50(7-8):1368-1370
The hole lifetime τp in the n-base and isothermal (pulse) current–voltage characteristics have been measured in 4H–SiC diodes with a 10 kV blocking voltage (100 μm base width). The τp value found from open circuit voltage decay (OCVD) measurements is 3.7 μs at room temperature. To the best of the authors’ knowledge, the above value of τp is the highest reported for 4H–SiC. The forward voltage drops VF are 3.44 V at current density j = 100 A/cm2 and 5.45 V at j = 1000 A/cm2. A very deep modulation of the blocking base by injected non-equilibrium carriers has been demonstrated. Calculations in term of a simple semi-analytical model describe well the experimental results obtained. 相似文献
11.
S. Tsukimoto K. Nitta T. Sakai M. Moriyama Masanori Murakami 《Journal of Electronic Materials》2004,33(5):460-466
In order to understand a mechanism of TiAl-based ohmic contact formation for p-type 4H-SiC, the electrical properties and
microstructures of Ti/Al and Ni/Ti/Al contacts, which provided the specific contact resistances of approximately 2×10−5 Ω-cm2 and 7×10−5 Ω-cm2 after annealing at 1000°C and 800°C, respectively, were investigated using x-ray diffraction (XRD) and high-resolution transmission
electron microscopy (HRTEM). Ternary Ti3SiC2 carbide layers were observed to grow on the SiC surfaces in both the Ti/Al and the Ni/Ti/Al contacts when the contacts yielded
low resistance. The Ti3SiC2 carbide layers with hexagonal structures had an epitaxial orientation relationship with the 4H-SiC substrates. The (0001)-oriented
terraces were observed periodically at the interfaces between the carbide layers and the SiC, and the terraces were atomically
flat. We believed the Ti3SiC2 carbide layers primarily reduced the high Schottky barrier height at the contact metal/p-SiC interface down to about 0.3
eV, and, thus, low contact resistances were obtained for p-type TiAl-based ohmic contacts. 相似文献
12.
The interfacial microstructural analysis of the Ge/Pd(Zn) ohmic contact to p-InP, based on the solid-phase regrowth principle,
is reported. Typical contact resistivities of low 10−4 to low 10−5 Ω-cm2 can be obtained for this contact scheme annealed at temperatures higher than 400°C. Cross-sectional transmission electron
microscopy, energy dispersive x-ray composition mapping, and con-verge beam electron diffraction were utilized in this study
for the interfacial microstructure analysis. The solid-phase regrowth process has been confirmed in this contact system on
InP. Precipitates of trapped materials during solid phase regrowth have also been observed. The correlation between the electrical
and microstructural properties is addressed. 相似文献
13.
Nakamura T. Miyanagi T. Kamata I. Jikimoto T. Tsuchida H. 《Electron Device Letters, IEEE》2005,26(2):99-101
In this letter, we report the fabrication of high-voltage and low-loss 4H-SiC Schottky-barrier diodes (SBDs) with a performance close to the theoretical limit using a Mo contact annealed at high-temperature. High-temperature annealing for the Mo contact was found to be effective in controlling the Schottky-barrier height at 1.2-1.3 eV without degradation of n-factor and reverse characteristics. We successfully obtained a 1-mm/sup 2/ Mo-4H-SiC SBD with a breakdown voltage (V/sub b/) of 4.15 kV and a specific on resistance (R/sub on/) of 9.07 m/spl Omega//spl middot/cm/sup 2/, achieving a best V/sub b//sup 2//R/sub on/ value of 1898 MW/cm/sup 2/. We also obtained a 9-mm/sup 2/ Mo-4H-SiC SBD with V/sub b/ of 4.40 kV and R/sub on/ of 12.20 m/spl Omega//spl middot/cm/sup 2/. 相似文献
14.
DeSalvo G.C. Quach T.K. Bozada C.A. Dettmer R.W. Nakano K. Gillespie J.K. Via G.D. Ebel J.L. Havasy C.K. 《Semiconductor Manufacturing, IEEE Transactions on》1995,8(3):314-318
A new III-V semiconductor device fabrication process for GaAs-based field effect transistors (FET) is presented which uses a single lithographic process and metal deposition step to form both the ohmic drain/source contacts and the Schottky gate contact concurrently. This single layer integrated metal FET (SLIMFET) process simplifies the fabrication process by eliminating an additional lithographic step for gate definition, a separate gate metallization step, and thermal annealing for ohmic contact formation. The SLIMFET process requires a FET structure which incorporates a compositionally graded InxGa1-xAs cap layer to form low resistance, nonalloyed ohmic contacts using standard Schottky metals. The SLIMFET process also uses a Si3N4 mask to provide selective removal of the InGaAs ohmic layers from the gate region prior to metallization without requiring an additional lithographic step. GaAs MESFET devices were fabricated using this new SLIMFET process which achieved DC and RF performance comparable to GaAs MESFET's fabricated by conventional methods 相似文献
15.
Okumura Y. Shirahata M. Hachisuka A. Okudaira T. Arima H. Matsukawa T. 《Electron Devices, IEEE Transactions on》1992,39(11):2541-2552
The source-to-drain nonuniformly doped channel (NUDC) MOSFET has been investigated to improve the aggravation of the V th lowering characteristics and to prevent the degradation of the current drivability. The basic concept is to change the impurity ions to control the threshold voltage, which are doped uniformly along the channel in the conventional channel MOSFET, to a nonuniform profile of concentration. The MOSFET was fabricated by using the oblique rotating ion implantation technique. As a result, the V th lowering at 0.4-μm gate length of the NUDC MOSFET is drastically suppressed both in the linear region and in the saturation region as compared with that of the conventional channel MOSFET. Also, the maximum carrier mobility at 0.4-μm gate length is improved by about 20.0%. Furthermore, the drain current is increased by about 20.0% at 0.4-μm gate length 相似文献
16.
C. Virojanadara P. -A. Glans T. Balasubramanian L. I. Johansson E. B. Macak Q. Wahab L. D. Madsen 《Journal of Electronic Materials》2002,31(12):1353-1356
The Schottky barrier height (SBH) of Au on 4H-SiC(0001) has been studied using photoemission and synchrotron radiation. The
Au was deposited in-situ on clean and well-ordered √3×√3 R30° reconstructed SiC surfaces prepared by in situ heating at ∼950°C.
The SBH was determined from the shift observed in the Si 2p core level, in addition to the initial band bending determined
for the clean surface. The results were compared with values obtained by electrical, capacitance-voltage (C-V), and current-voltage
(I-V) characterization methods. A favorable comparison between the three independent, SBH determination methods was found. 相似文献
17.
《Solid-state electronics》2006,50(9-10):1567-1578
Buried gate type p-base n-emitter soft contact (PNSC) structure 4 kV static induction thyristors (SIThys) have been fabricated in order to make thyristors for high-speed turn-on applications to such as high energy accelerators. It was found that these static induction thyristors could be fabricated under the test pilot line with a good device production yield. The static characteristics and pulse switching characteristics of these static induction thyristors are examined. Several application examples of the present 4 kV static induction thyristors to power supplies for high energy accelerators are shown. 相似文献
18.
《Electron Device Letters, IEEE》1987,8(1):30-32
Graded regions of n-(Ga,In)As and p-Ga(As,Sb) were incorporated side-by-side as emitter and base contacts, respectively, into an n-p-n (Al,Ga)As/GaAs heterostructure bipolar transistor (HBT). The process involved two separate molecular beam epitaxy (MBE) growths, leading to base contact regions that were self-aligned to the emitter mesas. The devices could be easily probed with pressure contacts even prior to any metallization, and excellent characteristics were obtained after final metallization. Contact resistivities of 5 × 10-7and 3 × 10-6Ω.cm2were measured for n- and p-type graded-gap ohmic contact structures, respectively. 相似文献
19.
Wilker C. Shen Z.-Y. Pang P. Face D.W. Holstein W.L. Matthews A.L. Laubacher D.B. 《Microwave Theory and Techniques》1991,39(9):1462-1467
The authors have fabricated high-temperature superconducting films made of TlBaCaCuO (2212) and YBaCuO (123) by postdeposition annealing techniques on (100) LaAlO3 substrates. These films, especially the TlBaCaCuO(2212), exhibit high temperature operation, high Q (low surface resistance), and low power dependence. Both types of films have measured surface resistances which are better than 1/10 that of copper to 20 GHz. Microstrip resonators with a fundamental resonance frequency of 5 GHz were fabricated from these materials. The performance of the best resonator at 90 K (loaded Q >20000 at 5 GHz) was 50 times better than an analogous copper resonator (also measured at 90 K) and can handle more than 10 W of peak power in the resonator with only a small degradation of the Q . In addition, the shift of the resonator frequencies with temperature was fit to a two-fluid model 相似文献