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Topic: HEMT

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	[No title] (Site not responding. Last check: 2007-10-18)
		A HEMT according to Claim 2 wherein: said passivation layer is on said second undoped aluminum nitride layer; said aluminum gallium nitride active structure comprises an undoped layer of aluminum gallium nitride; and said passivation layer is selected from the group consisting of silicon dioxide and silicon nitride.
		A HEMT according to Claim 13 wherein: said passivation layer is selected from the group consisting of silicon nitride and silicon dioxide; said heterojunction comprises adjacent layers of aluminum gallium nitride (AlGaN) and gallium nitride (GaN); and said HEMT further comprising an aluminum nitride buffer layer between said substrate and said heterojunction structure.
		A HEMT according to Claim 13 wherein: said ohmic contacts comprise an alloy of titanium, aluminum, and nickel and said rectifying gate contact is selected from the group consisting of titanium, platinum, chromium, alloys of titanium and tungsten, and platinum silicide; and said source and drain contacts comprise an alloy of titanium, silicon, and nickel.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=00/04587.011213&ELEMENT_SET=DECL (3757 words)

	Fujitsu Achieves Breakthrough Output with Gallium Nitride HEMT Amplifier : FUJITSU
		The higher the operating voltage of transmitter amplifiers is relative to the 48-volt operation voltage supplied in the base station system, the greater the increase of both efficiency and output of transmitter amplifiers.
		As demonstrated by these results, Fujitsu's new GaN HEMT amplifier delivers high performance to transmission amplifiers for 3G mobile communication base stations, contributing significantly to the development of base station systems that are smaller and more cost and energy efficient.
		HEMT: A field-effect transistor that takes advantage of operation of the electron layer at the boundary between different semiconductor materials that is relatively rapid compared to that within conventional semiconductors.
	www.fujitsu.com /global/news/pr/archives/month/2003/20031208-03.html (1126 words)

	Solid State Technology - Electronic transport characterization of HEMT structures
		HEMTs are not a new invention, but they are now coming to the forefront of the semiconductor industry because of their use in communication applications.
		The basis of HEMT materials is a lattice-matched heterojunction between two compound semiconductors, a donor and an acceptor.
		HEMTs became a prevailing choice for integrated circuit technologies in the mid-1980s owing to their superior high speed performance in logic applications.
	sst.pennnet.com /Articles/Article_Display.cfm?Article_ID=87698&CFID=79437&CFTOKEN=31363295 (2908 words)

	InP HEMT Technology Group at IFH (Site not responding. Last check: 2007-10-18)
		This is partly due to the physical dimensions of the sub-micron structure, which generates huge electric fields (close to the breakdown fieldstrength) and partly due to the low bandgap energy of the material system used.
		We improve the breakdown properties of our InP HEMTs trough a study of the device using a physical model of the material parameters and by analysing the effects of the geometrical device structure on the output characteristics.
		Knowledge of the electrical field (or potential distribution) within a HEMT device is crucial if one wants to compare simulated device properties with their measured equivalents.
	www.ifh.ee.ethz.ch /Microwave/InP/research.html (827 words)

	Fujitsu Develops Breakthrough Technology for Low-Cost Production of Gallium-Nitride HEMT : FUJITSU
		Because they can be driven at high voltages with excellent output performance and efficiency, there is much anticipation for GaN HEMT amplifiers that can be used as high-output amplifiers suitable for the next generation of mobile base stations.
		Fujitsu's breakthrough technology reduces production cost of GaN HEMT to less than one-third that of conventional levels by using conductive SiC substrates which are more economical than semi-insulating silicon carbide (SiC) substrates, thereby making it possible to manufacture low-cost GaN HEMT amplifiers.
		high electron mobility transistors (HEMT): A field-effect transistor that takes advantage of operation of the electron layer at the boundary between different semiconductor materials that is relatively rapid compared to that within conventional semiconductors.
	www.fujitsu.com /global/news/pr/archives/month/2004/20041221-01.html (1063 words)

	Radio-Electronics.Com :: High Electron Mobility Transistor (HEMT)
		The development of the HEMT took many years and it was not until many years after the basic FET was established that the HEMT appeared on the market.
		The key element within a HEMT is thespecialised pn junction that it uses.
		The operation of the HEMT is somewhat different to other types of FET and as a result it is able to give a very much improved performance over the standard junction or MOS FETs.
	www.radio-electronics.com /info/data/semicond/hemt/hemt.php (876 words)

	NASA Tech Briefs: 80-GHz MMIC HEMT voltage-controlled oscillator (Site not responding. Last check: 2007-10-18)
		The other HEMT serves mainly as a varactor for controlling the frequency: the frequency-control element is its gate-to-source capacitance, which is varied by changing its gate supply voltage.
		The gain HEMT is biased for class-A operation (meaning that current is conducted throughout the oscillation cycle).
		For example, one HEMT VCO reported in the literature had an output power of 7 dBm (==5 mW) and a tuning range 2GHz wide centered approximately at a nominal frequency of 77 GHz.
	www.findarticles.com /p/articles/mi_qa3957/is_200302/ai_n9190583 (411 words)

	HEMT polarimeters, or correlation receivers, are much more common in current CMBR polarization experiments than ... (Site not responding. Last check: 2007-10-18)
		HEMT polarimeters, or correlation receivers, are much more common in current CMBR polarization experiments than bolometers bec
		HEMT polarimeters and correlation receivers are much more common in current CMBR polarization experiments than bolometers because of their higher sensitivity below observing frequencies of 100GHz and their lower susceptibility to systematic effects (Gaier, 2003).
		Noise- HEMT amplifiers should be low noise so that the small signal from the sky is detectable in a reasonable amount of time.
	cfcp.uchicago.edu /~peterh/polarimetry/hemt.html (1613 words)

	Japan breaks own record for fastest HEMT (Site not responding. Last check: 2007-10-18)
		The previous HEMT world record, 398 GHz, was set at the Communications Research Laboratory (CRL) this spring.
		Earlier this year, Fujitsu Labs Fellow Takashi Mimura, who invented the HEMT in 1979, told EE Times he was pessimistic about HEMTs breaking the 500-GHz barrier until gate lengths came down to a difficult-to-manufacture 10 nm.
		A 400-GHz-capable HEMT at 60 GHz, for example, achieves about double the gain of the most powerful 150-GHz gallium-arsenide models.
	www.commsdesign.com /printableArticle?articleID=12806139 (744 words)

	January 1998, Minutes of MMA Receiver Group meeting
		It was Marian Pospieszalski's feeling that the noise temperature penalty at 40K (vs. 15K) would be unacceptable for the HEMT receivers, although no quantitative study of the tradeoffs has been done.
		One option is to implement only one or two stages of amplification at 4K, with the rest at the warm stage (see Attachment B); Marian pointed out the extra cost of construction due to additional amplifier blocks, and possible difficulties in interstage coupling if 30-50 cm of separation is needed.
		In addition, it is assumed that all HEMT amplifiers not in use will have zero bias applied, resulting in (typically) four simultaneously active channels (out of 84+22=36 channels total).
	www.tuc.nrao.edu /alma/workgroups/receiver.98.01.html (880 words)

	Low Phase Noise GaN HEMT Oscillator
		The purpose of this work is to use simple oscillator circuits to check the phase-noise properties of GaN HEMT.
		A common gate Colpitts oscillator structure was used, because its simplicity helps to control the both active and passive components.
		The oscillator, based on an 2x100um wide AlGaN/GaN HEMT, delivers 20.7 dBm output power at 5 GHz with phase noise of -105 dBc/Hz at a 100 kHz offset.
	my.ece.ucsb.edu /hongtao/research/gan_osci.htm (156 words)

	Synopsys Products - Full TCAD-based Device Characterization: HEMT (Site not responding. Last check: 2007-10-18)
		In this section a standard HEMT structure is introduced.
		Using the recommended standard model set for HEMT devices, all device characteristics are simulated with the general purpose device simulator DESSIS.
		Sketch of the layer structure of the physical 2D HEMT model used.
	www.synopsys.com /products/tcad/examples/hemt.html (725 words)

	hemt
		The material properties that have the greatest impact on the high-speed performance of HEMTS are the sheet charge density in the two-dimensional electron gas and the effective electron velocity.
		An scanning electron micropscope picture of a HEMT with gate length of 0.2 mm and source-drain spacing of 1.0 mm is shown above on the right.
		InAs HEMTs provide equivalent high-speed figure-of-merit performance at 5 to 10 times lower power dissipation as compared to state-of-the-art InAlAs/InGaAs/InP HEMTs with the same gate length (0.1 mm).
	estd-www.nrl.navy.mil /code6870/epicenter/hemt/hemthome.html (748 words)

	Automated wafer inspection aids GaN HEMT morphology (April 2005) - Compound Semiconductor magazine - Compound ...
		By assigning brightness levels proportional to the amplitude of the detected signal, output from the various detectors can also be converted into images similar to those produced by a microscope.
		Figure 3 shows images of the GaN HEMT surface obtained from a microscope and the SZc signal from an OSA.
		Using an OSA to investigate the epiwafer quality of GaN HEMTs has enabled defects in the substrate, such as micropipes that cause many surface defects, to be distinguished from their epi-originating counterparts.
	compoundsemiconductor.net /articles/magazine/11/4/2/1 (1190 words)

	[No title] (Site not responding. Last check: 2007-10-18)
		Currently three methods for modeling the small signal characteristics of HEMT devices are known: equivalent circuit modeling; physical device simulation; and analytical physical device modeling.
		In the case of HEMT devices, a typical small signal and noise equivalent circuit topology is shown with FIG.
		In particular, the noise generator model elements are derived from a current/voltage perturbation analysis of the intrinsic charge and electric fields as modeled within the device by the semi-physical HEMT model.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=01/84381.011108&ELEMENT_SET=DECL (6764 words)

	[No title] (Site not responding. Last check: 2007-10-18)
		InP HEMT: Toshiba believes that InP LN HEMTs are crucial for the 21 GHz receiver needed in 1997 for HDTV satellites.
		HEMTs are needed for 12 GHz DBS (not MESFETs).
		The HEMT and HBT work is carried out in the ULSI division with about 200 researchers.
	www.tokyo.afosr.af.mil /OldReports/9508.html (1906 words)

	5. III-V DEVICES AND CIRCUITS
		More advanced high electron mobility transistor (HEMT) devices are the preferred choice for higher frequency and higher performance applications with lower noise figures for low noise amplifiers.
		TRW recently demonstrated the world's first 190 GHz InP HEMT low noise amplifier (LNA), which exhibited a gain of more than 7 dB from 160 - 190 GHz, with a peak of 9.6 dB, while the noise figure is 6 dB at 170 GHz (see Fig.
		For applications at somewhat lower frequencies, GaAs HEMT (PHEMT or pseudomorphic HEMT) is a very practical and readily available device.
	www.wtec.org /loyola/wireless/05_03.htm (497 words)

	Print Version (Site not responding. Last check: 2007-10-18)
		The technology is claimed to reduce GaN HEMT production costs to less than one-third that of conventional levels, thereby contributing to the realization of lower-cost GaN HEMT-based amplifiers.
		It was achieved by forming an aluminum nitride (AlN) epitaxial layer of 10 micrometers or more on the conductive n-type SiC substrate, followed by an epitaxial layer of GaN HEMT developed on top of this substrate.
		AIN was grown on a n-SiC using hydride vapor phase epitaxy and GaN HEMT was grown on AIN using metal organic vapor phase epitaxy.
	www.eetasia.com /ARTP_8800354927_0.HTM (288 words)

	MMIC Semiconductor Tradeoffs - Microwave Encyclopedia - Microwaves101.com
		Including HEMT and HBT technologies, literally billions of dollars have been spent extending fmax of GaAs products up into 100s of GHz.
		Indium phosphide HEMT has broken all of the upper frequency records, on the way to terahertz devices.
		However, there are serious drawbacks to this technology, not the least of which is it's high cost.
	www.microwaves101.com /encyclopedia/MMICsemi.cfm (1663 words)

	Fujitsu Develops Breakthrough Technology for Low-Cost Production of Gallium-Nitride HEMT
		Fujitsu has verified that amplifiers using its proprietary GaN HEMT technology in combination with its distortion compensation circuits(3) can achieve superior efficiency and output levels for use in 3G and future generations of mobile base stations.
		However, technological issues to overcome for practical application of conductive SiC substrate were that parasitic capacitance(5) between an electrode pad and a conductive SiC substrate leads to lower gain(6), and increase of current leakage to the conductive SiC substrate.
		AIN was grown on a n-SiC using hydride vapor phase epitaxy(7) and GaN HEMT was grown on AIN using metal organic vapor phase epitaxy(8).
	www.physorg.com /news2466.html (1152 words)

	NASA Tech Briefs: MMIC HEMT power amplifier for 140 to 170 GHz
		Hence, this amplifier could serve as a prototype of amplifiers to be incorporated into heterodyne radiometers used in atmospheric science.
		The original intended purpose served by this amplifier is to boost the signal generated by a previously developed 164-GHz MMIC HEMT doubler [which was described in "164-GHz MMIC HEMT Frequency Doubler" (NPO-21197), NASA Tech Briefs, Vol.
		Each HEMT is characterized by gate-periphery dimensions of 4 by 37 [mu]m.
	www.findarticles.com /p/articles/mi_qa3957/is_200311/ai_n9333296 (468 words)

	Characterization of the Rhodobacter sphaeroides 5-aminolaevulinic acid synthase isoenzymes, HemA and HemT, isolated ... (Site not responding. Last check: 2007-10-18)
		Characterization of the Rhodobacter sphaeroides 5-aminolaevulinic acid synthase isoenzymes, HemA and HemT, isolated from recombinant Escherichia coli -- Bolt et al.
		The spectrum of PLP contains absorption maxima at 326 and 380 and these maxima are also mirrored in the spectrum of HemT indicating that the PLP is not associating with the protein through an internal aldimine linkage.
		HemT expressed without the GST fusion (data not shown).
	content.febsjournal.org /cgi/content/full/265/1/290 (5520 words)

	New Evidence for Velocity Overshoot in a 200 nm Pseudomorphic HEMT
		New Evidence for Velocity Overshoot in a 200 nm Pseudomorphic HEMT
		Although there are some explanations in the literature for why such discrepancies between the predicted and extracted effective velocity in HEMTs exist [10], they are based on Monte Carlo simulation itself without direct links to real fabricated and measured devices.
		Based on Monte Carlo simulation [10] it was clearly demonstrated that the major error in the experimental estimation of the effective channel velocity in deep submicrometer HEMT is introduced by neglecting the fringing effects which modify both the effective channel length and the gate-to source capacitance.
	www.elec.gla.ac.uk /groups/dev_mod/papers/essderc/essderc.html (3475 words)

	InP HEMT MMIC Low-Noise Amplifier for 65 to 110 GHz
		InP HEMT MMIC Low-Noise Amplifier for 65 to 110 GHz
		This MMIC incorporates TRW's state-of-the-art, InP-based, high-electron-mobility transistors (HEMTs) coupled with coplanar-waveguide (CPW) transmission lines, thin-film resistors, and thin-film capacitors.
		The MMIC is mounted in a waveguide module with CPW-to-waveguide transitions of the probe type (see figure).
	www.nasatech.com /Briefs/Feb02/NPO20752.html (330 words)

	GaN HEMT features high power density (December 2003) - News - Compound Semiconductor
		A GaN HEMT developed by TriQuint Semiconductor and Lockheed Martin has record power density, power-added efficiency and RF lifetime, say the companies.
		The high-performance transistor, which was fabricated using an ‘advanced gate process’, features nearly 12W/mm CW power and more than 50% power-added efficiency at 10GHz.
		TriQuint says that its proprietary process increases GaN HEMT power density 50 percent beyond that of more conventional E-beam T-gate devices.
	compoundsemiconductor.net /articles/news/7/12/2/1 (298 words)

	Fujitsu achieves breakthrough output with Gallium Nitride HEMT amplifier
		Fujitsu Laboratories announced that it has developed a gallium nitride (GaN) high electron mobility transistor (HEMT) amplifier which achieves the world's highest power output of 174 watts at 63 volts, while demonstrating unprecedented record drain efficiency of 40%, fulfilling W-CDMA system requirements for base stations.
		Up until now, Fujitsu used its proprietary GaN HEMT technology in conjunction with distortion compensation circuits, demonstrating that the technology would be applicable to 3G mobile base-station amplifiers that operate at high efficiency.
		Fujitsu's GaN HEMT amplifier, when supplied with 60 or more volts of power, satisfies the W-CDMA specification for adjacent channel leakage, while also achieving the record-setting drain efficiency of 40%.
	www.3gnewsroom.com /3g_news/dec_03/news_4022.shtml (555 words)

	Integration of HEMT's and RTD's for Communications Circuits (Site not responding. Last check: 2007-10-18)
		The results demonstrated so far are based on RTD-Schottky diode circuits, which suffer from the limitations common to circuits based on two-terminal devices, namely, lack of input/output isolation and limited fan out.
		In this work we propose to research and develop the monolithic integration of high electron mobility transistors (HEMTs), RTDs, and Schottky diodes.
		In particular, we will address materials, device design and fabrication issues, together with their impact on circuit performance.
	www.ucop.edu /research/micro/abstracts/98_165.html (221 words)

	CommsDesign - Emcore teams with Rockwell Scientific in GaN HEMT power amps (Site not responding. Last check: 2007-10-18)
		Also, Emcore has agreed to supply GaN HEMT epitaxial wafers to Rockwell Scientific, which will provide information about the behavior of the devices as well as material-device correlation so that Emcore can optimize its wafer processes.
		The company added that the linearity of gallium-nitride HEMTs makes them attractive for use in power amplifiers in cellular base station applications.
		Critical to greater use of GaN HEMTs is material uniformity and reproducibility, noted Karim Boutros, senior scientist and head of the GaN effort at the Thousand Oaks-based company.
	www.commsdesign.com /news/tech_beat/OEG20020402S0024 (544 words)

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