R. Jefferies
Qinetiq
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Publication
Featured researches published by R. Jefferies.
international electron devices meeting | 2008
Marko Radosavljevic; T. Ashley; Aleksey D. Andreev; Stuart D. Coomber; Gilbert Dewey; M. T. Emeny; M. Fearn; D.G. Hayes; Keith P. Hilton; Mantu K. Hudait; R. Jefferies; T. Martin; Ravi Pillarisetty; Titash Rakshit; Stephen L. J. Smith; Michael J. Uren; David J. Wallis; P. J. Wilding; Robert S. Chau
This paper describes for the first time, a high-speed and low-power III-V p-channel QWFET using a compressively strained InSb QW structure. The InSb p-channel QW device structure, grown using solid source MBE, demonstrates a high hole mobility of 1,230 cm2/V-s. The shortest 40 nm gate length (LG) transistors achieve peak transconductance (Gm) of 510 muS/mum and cut-off frequency (fT) of 140 GHz at supply voltage of 0.5V. These represent the highest Gm and fT ever reported for III-V p-channel FETs. In addition, effective hole velocity of this device has been measured and compared to that of the standard strained Si p-channel MOSFET.
international electron devices meeting | 2005
Suman Datta; T. Ashley; J. Brask; L. Buckle; Mark Beaverton Doczy; M. T. Emeny; D.G. Hayes; Keith P. Hilton; R. Jefferies; T. Martin; T.J. Phillips; David J. Wallis; P. J. Wilding; Robert S. Chau
We demonstrate for the first time 85nm gate length enhancement and depletion mode InSb quantum well transistors with unity gain cutoff frequency, fT, of 305 GHz and 256 GHz, respectively, at 0.5V VDS, suitable for high speed, very low power logic applications. The InSb transistors demonstrate 50% higher unity gain cutoff frequency, fT, than silicon NMOS transistors while consuming 10 times less active power
international conference on solid state and integrated circuits technology | 2004
T. Ashley; A.R. Barnes; L. Buckle; Suman Datta; A.B. Dean; M.T. Emery; M. Fearn; D.G. Hayes; Keith P. Hilton; R. Jefferies; T. Martin; K.J. Nash; T.J. Phillips; W.A. Tang; P. J. Wilding; Robert S. Chau
InSb-based quantum well field-effect transistors, with gate length down to 0.2 /spl mu/m, are fabricated for the first time. Hall measurements show that room temperature electron mobilities over 30,000 cm /sup 2/V/sup -1/s/sup -1/ are achieved with a sheet carrier density over 1/spl times/10/sup 12/ cm/sup -2/ in a modulation doped InSb quantum well with Al/sub x/In/sub 1-x/Sb barrier layers. Devices with 0.2 /spl mu/m gate length and 20% Al barrier exhibit DC transconductance of 625 /spl mu/S//spl mu/m and f/sub T/ of 150 GHz at V/sub DS/ =0.5V. 0.2 /spl mu/m devices fabricated on 30% Al barrier material show DC transconductance of 920 /spl mu/S//spl mu/m at V/sub DS/ = 0.5 V. Benchmarking against state-of-the-art Si MOSFETs indicates that InSb QW transistors can achieve equivalent high speed performance with 5-10 times lower dynamic power dissipation and therefore are a promising device technology to complement scaled silicon-based devices for very low power, ultra-high speed logic applications.
international electron devices meeting | 1997
T. Ashley; A.B. Dean; Charles Thomas Elliott; R. Jefferies; F. Khaleque; T.J. Phillips
High-speed, low-power consumption field-effect transistors fabricated from InSb/In/sub 1-x/Al/sub x/Sb are demonstrated. A 0.7 /spl mu/m gate-length enhancement-mode device shows an f/sub T/, of 74 GHz, and an f/sub max/ of 89 GHz, at a drain voltage below 0.5 V. This is the fastest reported transistor for its gate length, as far as is known.
international electron devices meeting | 2009
T. Ashley; M. T. Emeny; D.G. Hayes; Keith P. Hilton; R. Jefferies; Jessica O. Maclean; S. J. Smith; A. W-H Tang; David J. Wallis; P. J. Webber
Indium antimonide (InSb) has the highest electron mobility and saturation velocity of any conventional semiconductor, giving potential for a range of analogue and digital ultra-high speed, low power dissipation applications. N-channel quantum well FETs have been fabricated with current gain cut-off frequency (fT) of more than 250 GHz and power gain cut-off frequency (fmax) of 500 GHz. Outline designs confirm the potential for multi-stage low noise amplifiers operating at more than 200 GHz, for applications such as integrated passive millimetre wave imaging.
compound semiconductor integrated circuit symposium | 2006
T. Ashley; L. Buckle; M. T. Emeny; M. Fearn; D.G. Hayes; Keith P. Hilton; R. Jefferies; T. Martin; T.J. Phillips; Jeff Powell; A.W.H. Tang; David J. Wallis; P.J. Wilding
Indium antimonide has the highest electron mobility and saturation velocity of any semiconductor, so gives the prospect of extremely high frequency operation with very low power dissipation. We report uncooled transistors with cut-off frequency of 340 GHz at a source-drain voltage of 0.5 V, leading towards this goal
Electronics Letters | 2007
T. Ashley; L. Buckle; Suman Datta; M. T. Emeny; D.G. Hayes; Keith P. Hilton; R. Jefferies; T. Martin; T.J. Phillips; David J. Wallis; P. J. Wilding; Robert S. Chau
Archive | 2010
David J. Wallis; R. Jefferies
Archive | 2009
T. Ashley; K. L. Adamson; Graham J. Ball; P. D. Buckle; Dianne J. Hall; D.G. Hayes; Keith P. Hilton; R. G. Humphreys; R. Jefferies; David J. Lees; Jessica O. Maclean; A.G. Munday; Neil A. Salmon; W. H. A. Tang
european microwave integrated circuits conference | 2010
T. Ashley; M. T. Emeny; D.G. Hayes; Keith P. Hilton; R. Jefferies; Jessica O. Maclean; S. J. Smith; W. H. A. Tang; P. J. Webber; G. M. Williams