| 1. |
- Amirmazlaghani, Mina, 1984, et al.
(författare)
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Graphene-Si Schottky IR Detector
- 2013
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Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 49:7, s. 589-594
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on photodetection properties of graphene-Si schottky junction by measuring current-voltage characteristics under 1.55µm excitation laser. The measurements have been done on a junction fabricated by depositing mechanically exfoliated natural graphite on top of the pre-patterned silicon substrate. The electrical Schottky barrier height is estimated to be (0.44-0.47) eV with a minimum responsivity of 2.8mA/W corresponding to an internal quantum efficiency of 10% which is almost an order of magnitude larger than regular Schottky junctions. A possible explanation for the large quantum efficiency related to the 2-D nature of graphene is discussed. Large quantum efficiency, room temperature IR detection, ease of fabrication along with compatibility with Si devices can open a doorway for novel graphene-based photodetectors.
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| 2. |
- ANDERSSON, MICHAEL, 1988, et al.
(författare)
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10 dB small-signal graphene FET amplifier
- 2012
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 48:14, s. 861-863
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Tidskriftsartikel (refereegranskat)abstract
- Reported is the realisation of a graphene FET microwave amplifier operating at 1 GHz, exhibiting a small-signal power gain of 10 dB and a noise figure of 6.4 dB. The amplifier utilises a matching inductor on the gate yielding a return loss of 20 dB. The design is optimised for maximum gain and the optimum noise figure is extracted by noise modelling and predicted to be close to 1 dB for the intrinsic graphene FET at this frequency. The presented results complement existing graphene FET applications and are promising for future graphene microwave circuits.
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| 3. |
- ANDERSSON, MICHAEL, 1988, et al.
(författare)
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Noise Figure Characterization of a Subharmonic Graphene FET Mixer
- 2012
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Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781467310871
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Konferensbidrag (refereegranskat)abstract
- We report on the first room temperature noise figure measurement of a graphene FET subharmonic resistive mixer in the interval fRF = 2-5 GHz. Due to an 8 nm thin Al2O3 gate dielectric it can operate with a conversion loss in the range 20-22 dB at only 0 dBm of local oscillator power. The measurement yields a noise figure close to the conversion loss, thus determining the noise to be thermal in origin, which is promising for cryogenic applications. The general route to lower noise figure is an improvement of the conversion loss.
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| 4. |
- ANDERSSON, MICHAEL, 1988, et al.
(författare)
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Resistive Graphene FET Subharmonic Mixers: Noise and Linearity Assessment
- 2012
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 60:12, s. 4035-4042
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first complete RF characterization of graphene field-effect transistor subharmonic resistive mixers in the frequency interval 2–5 GHz. The analysis includes conversion loss (CL), noise figure (NF), and intermodulation distortion. Due to an 8-nm thin Al2O3 gate dielectric, the devices operate at only 0 dBm of local oscillator (LO) power with an optimum measured CL in the range of 20–22 dB. The NF closely mimics the CL, thus determining the noise to be essentially thermal in origin, which is promising for cryogenic applications. The highest input third-order intercept point is measured to be 4.9 dBm at an LO power of 2 dBm.
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| 5. |
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| 6. |
- Barrientos, C. Z., et al.
(författare)
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Vertically illuminated TW-UTC photodiodes for terahertz generation
- 2010
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Ingår i: 21st International Symposium on Space Terahertz Technology 2010, ISSTT 2010; Oxford; United Kingdom; 23 March 2010 through 25 March 2010. - 9781617823626 ; , s. 405-408
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Konferensbidrag (refereegranskat)abstract
- More efficient continuous-wave photonic nearinfrared mixers as terahertz sources are investigated with the motivation to develop a universal photonic local oscillator for astronomical submillimeter/terahertz receiver systems. For this, our group has developed new concepts for vertically illuminated traveling-wave (TW) photomixers. The new device called TWUni- Travelling Carrier photodiodes (TW-UTC PD) was simulated, modeled and shall be optical/terahertz tested at the Electrical Engineering Department of the University of Chile, whereas device fabrication is performed at the MC2 cleanroom facility at Chalmers University of technology. We are reporting on first progresses in this direction.
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| 7. |
- Barrientos Z, C. M., et al.
(författare)
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Vertically illuminated TW-UTC photodiodes for terahertz generation
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819491534 ; 8452
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Konferensbidrag (refereegranskat)abstract
- More efficient and powerful continuous-wave photonic mixers as terahertz sources are motivated by the need of more versatile local oscillators for submillimeter/terahertz receiver systems. Uni-Travelling Carrier (UTC) photodiodes are very prospective candidates for reaching this objective, but so far only have been reported as lumped-elements or as edge-illuminated optical-waveguide travelling-wave (TW) devices. To overcome the associated power limitations of those implementations, we are developing a novel implementation of the UTC photodiodes which combines a traveling-wave photomixer with vertical velocity-matched illumination in a distributed structure. In this implementation called velocity-matched travelling-wave uni-travelling carrier photodiode, it is possible to obtain in-situ velocity matching of the beat-fringes of the two angled laser beams with the submm/THz-wave on the stripline. In this way, minimum frequency roll-off is achieved by tuning the angle between the two laser beams. A first design of these TW-UTC PDs from our Terahertz Photonics Laboratory at University of Chile has been micro-fabricated at the MC2 cleanroom facility at Chalmers Technical University.
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| 8. |
- Barrientos Z, C. M., et al.
(författare)
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Vertically illuminated TW-UTC photodiodes for terahertz generation
- 2010
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819482310 ; 7741
-
Konferensbidrag (refereegranskat)abstract
- More efficient continuous-wave photonic nearinfrared mixers as terahertz sources are investigated with the motivation to develop a universal photonic local oscillator for astronomical submillimeter/terahertz receiver systems. For this, we develop new concepts for vertically illuminated traveling-wave (TW) photomixers, TW Uni-Travelling Carrier (UTC) photodiodes. Device simulation/modeling and optical/terahertz testing is being done in the new terahertz photonics laboratory at the Electrical Engineering Department of the University of Chile, whereas device fabrication is performed at the MC2 cleanroom facility at Chalmers Technical University. We report on first progress in this direction.
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| 9. |
- Bryllert, Tomas, 1974, et al.
(författare)
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A 175 GHz HBV Frequency Quintupler With 60 mW Output Power
- 2012
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Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 22:2, s. 76-78
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we present a fixed tuned 175 GHz frequency quintupler with 60 mW output power. The peak efficiency is 6.3% and the 3 dB bandwidth is 8 GHz. The multiplier is based on a single Heterostructure Barrier Varactor (HBV) diode that is flip-chip soldered into a microtsrip matching circuit. All the matching is done “on-chip” and there is no need for dc bias. The multiplier block is very compact (25 x 9 x 8 mm^3).
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| 10. |
- Bryllert, Tomas, 1974, et al.
(författare)
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A broadband heterostructure barrier varactor tripler source
- 2010
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Ingår i: 2010 IEEE MTT-S International Microwave Symposium (MTT). - 0149-645X. - 9781424460571 ; , s. 344-347
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Konferensbidrag (refereegranskat)abstract
- We present the first demonstration of a broadband Heterostructure Barrier Varactor tripler, designed to cover a major part of the WR-8 waveguide band. The source comprises a waveguide housing, a six-barrier InP-HBV diode flip-chip mounted on an AlN microstrip filter circuit. The conversion loss 3-dB bandwidth was measured to 17 % at a center frequency of 112 GHz. The maximum output power was more than 15 mW for an input power of 300 mW. There are no mechanical tuners or DC-bias, which simplifies assembly and allows for ultra-compact design.
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