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Silicon Carbide Microwave Transistors and Amplifiers
Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
2005 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Ibis work deals with silicon carbide (SiC) metal semieonduetor field effect transistors (MESFETs) and microwave amplifiers using them. The wide bandgap (WBG) semiconductors silicon carbide and gallium nitride have a large potential for microwave power generation. The high power density combined with the comparably high impedance attainable by devices in these materials also offers new possibilities for wideband high power microwave systems. To realise these possibilities we need transistors that are well understood and optimised and amplifier designs that take advantage of the broadband possibilities offered by the transistors.

We have developed and used physical drift-diffusion simulation models for SiC MESFETs. The simulation results showed a large influence of the doping and thickness of the channel and buffer layers, and the properties of the semi-insulating substrate on the DC and small signal device performance. A comparison between the physical simulations and measured device characteristics has also been carried out. A novel and efficient way to extend the physical simulations to the large signal high frequency domain has been developed. The method was used to investigate experimentally detected problems in the dynamies of the transistors during large signal operation and to further optimise the device structure.

In this work a number of broadband SiC MESFET amplifiers were designed, fabricated and characterized. The packaging and charaeterisation of transistors is described and the design and characterisation of the amplifiers are presented.

A 100-500 MHz amplifier showed a measured output power above 20 W and gain >15 dB across the band and a peak power of 26 W at 400 MHz, corresponding to a power density of 5.2 W/mm, with an associated power added efficiency (PAE) of 46 %. A 0.8-2 GHz feedback amplifier showed a measured output power above 5 W, gain >7 dB and PAE above 15 % across the band. A two stage 2.8-3.3 GHz amplifier had a maximum measured output power of 12.6 W with 22 dB gain and 9% PAE measured at 2.8 GHz. These results clearly show that SiC devices have a large potential for microwave power amplifiers in general and broadband amplifiers in particular.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2005. , 44 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1186
Keyword [en]
SiC, MESFET, Physical simulations, Microwave power amplifier
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:liu:diva-31212Local ID: LiU-TEK-LIC-2005:41ISBN: 91-85457-03-5 (print)OAI: oai:DiVA.org:liu-31212DiVA: diva2:252035
Presentation
(English)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2010-02-25Bibliographically approved
List of papers
1. Physical simulations on the Operation of 4H-SiC Microwave Power Transistors
Open this publication in new window or tab >>Physical simulations on the Operation of 4H-SiC Microwave Power Transistors
2000 (English)In: Materials Science Forum Vols. 338-342, Scientific.Net , 2000, 1263-1266 p.Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Scientific.Net, 2000
Series
Materials Science Forum, ISSN 1662-9752 ; 338-342
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-53034 (URN)10.4028/www.scientific.net/MSF.338-342.1263 (DOI)
Conference
ICSCRM'99: 8th International Conference on Silicon Carbide and Related Materials, Research Triangle Park, North Carolina, USA, October 10-15, 1999
Available from: 2010-01-14 Created: 2010-01-14 Last updated: 2015-02-27
2. A comparison between physical simulations and experimental results in 4H-SiC MESFETs with non-constant doping in the channel and buffer layers
Open this publication in new window or tab >>A comparison between physical simulations and experimental results in 4H-SiC MESFETs with non-constant doping in the channel and buffer layers
Show others...
2001 (English)In: Maretials Science Forum Vols. 353-356, Stafa-Zurich, Switzerland: Trans Tech Publications Inc., 2001, Vol. 353-356, 699-702 p.Conference paper, Published paper (Refereed)
Abstract [en]

The performance of SiC MESFETs, fabricated on a structure with non-constant doping-profiles in the channel and buffer layers have been studied. A good correspondence between experimental DC-characteristics and physical simulations was obtained, when using the doping profiles from SIMS measurements.

Place, publisher, year, edition, pages
Stafa-Zurich, Switzerland: Trans Tech Publications Inc., 2001
Series
Materials Science Forum, ISSN 1662-9752 ; 353-356
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-53037 (URN)10.4028/www.scientific.net/MSF.353-356.699 (DOI)
Conference
ECSCRM 2000: 3rd European Conference on Silicon Carbide and Related Materials, 3-7 September 2000, Kloster Banz, Germany
Available from: 2010-01-14 Created: 2010-01-14 Last updated: 2015-04-09
3. Evaluation of SiC MESFET structures using large-signal time-domain simulations
Open this publication in new window or tab >>Evaluation of SiC MESFET structures using large-signal time-domain simulations
Show others...
2002 (English)In: Materials Science Forum Vols. 389-393, 2002, Vol. 389-3, 1395-1398 p.Conference paper, Published paper (Refereed)
Abstract [en]

When designing transistors for microwave power applications a good understanding of their large signal behaviour in a real circuit context is essential. We have used the device simulator Medici in a novel way to simulate the large signal high frequency time domain properties of different SiC MESFET structures. The simulations show that even for transistors with good DC properties the exact design of the channel-buffer and the buffer-substrate regions is important when a good high power RF performance is required. Our simulations indicate that output power densities above 6W/mm are possible if heating problems are solved.

Keyword
large-signal, MESFETs, microwave, power, simulation, time-domain
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-48829 (URN)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2010-02-25
4. Computational load pull simulations of SiC microwave power transistors
Open this publication in new window or tab >>Computational load pull simulations of SiC microwave power transistors
2003 (English)In: Solid-State Electronics, ISSN 0038-1101, Vol. 47, no 11, 1921-1926 p.Article in journal (Refereed) Published
Abstract [en]

The design of power transistors for microwave applications requires a good understanding of their large signal behaviour in a real circuit context. The computational load-pull simulation technique is a powerful new way to evaluate the full time-domain voltages and currents of microwave power transistors during realistic operation. With this method it is possible to relate details in the time domain voltages and currents to corresponding variations in carrier densities, electrical field, etc. in the device. We have utilised the standard device simulator Medici, directly driven by sine voltage sources on both input and output. The resulting data from the simulations was then analysed using Matlab. Several 4H-SiC MESFET structures were evaluated by this technique and we found the p-type buffer layer doping and thickness to be crucial to obtain an optimum RF power. A 4H-SiC MESFET structure was found to have an output power of 6.2 W/mm at 1 GHz. ⌐ 2003 Elsevier Ltd. All rights reserved.

Keyword
Physical large signal modelling; Time-domain; Simulation; SiC; MESFET; Microwave; Load-pull
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-34759 (URN)10.1016/S0038-1101(03)00251-X (DOI)23131 (Local ID)23131 (Archive number)23131 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2010-02-25
5. DC and RF performance of insulating gate 4H-SiC depletion mode Field Effect Transistors
Open this publication in new window or tab >>DC and RF performance of insulating gate 4H-SiC depletion mode Field Effect Transistors
2004 (English)In: Materials Science Forum, Vols. 457-460, 2004, Vol. 457-460, 1225-1228 p.Conference paper, Published paper (Refereed)
Abstract [en]

A depletion mode 4H-SiC MOSFET for RT applications is studied using drift-diffusion physical device simulations. The structure is basically the same as for a MESFET. A MOS gate with a 30 nm thick SiO2 layer replaces the Schottky gate. A 40% increase in the drain current was observed for a positive gate bias of 7 V compared to 0 V. The small signal AC analysis showed f(T) and f(max) to be 15.7 and 52.9 GHz respectively.

Keyword
RF power transistors; MOSFETs; depletion mode transistors
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-53522 (URN)10.4028/www.scientific.net/MSF.457-460.1225 (DOI)
Conference
ICSCRM2003
Available from: 2010-01-25 Created: 2010-01-25 Last updated: 2010-12-13
6. Broadband RF SiC MESFET power amplifiers
Open this publication in new window or tab >>Broadband RF SiC MESFET power amplifiers
2005 (English)In: Materials Science Forum, ISSN 0255-5476, Vol. 483, 857-860 p.Article in journal (Refereed) Published
Abstract [en]

We have designed and characterized preliminary versions of two wideband SiC-based RF power amplifiers using SiC MESFETs from Chalmers University and Lateral Epitaxy SiC MEESFETs fabricated at AMDS AB. When optimized transistors are available they will be used in the design of amplifiers for a 100-500 MHz multifunction EW system.

Keyword
SiC; broadband; amplifier; RF; linearity
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-53513 (URN)10.4028/www.scientific.net/MSF.483-485.857 (DOI)
Available from: 2010-01-25 Created: 2010-01-25 Last updated: 2010-03-08

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