| 1. |
- Amirmazlaghani, Mina, 1984, et al.
(författare)
-
Graphene-Si Schottky IR Detector
- 2013
-
Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 49:7, s. 589-594
-
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.
|
|
| 2. |
- ANDERSSON, MICHAEL, 1988, et al.
(författare)
-
10 dB small-signal graphene FET amplifier
- 2012
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 48:14, s. 861-863
-
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.
|
|
| 3. |
- ANDERSSON, MICHAEL, 1988, et al.
(författare)
-
Noise Figure Characterization of a Subharmonic Graphene FET Mixer
- 2012
-
Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781467310871
-
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.
|
|
| 4. |
- ANDERSSON, MICHAEL, 1988, et al.
(författare)
-
Resistive Graphene FET Subharmonic Mixers: Noise and Linearity Assessment
- 2012
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 60:12, s. 4035-4042
-
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.
|
|
| 5. |
|
|
| 6. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
A novel catadioptric dielectric lens for microwave and terahertz applications
- 2008
-
Ingår i: Microwave and Optical Technology Letters. - : Wiley. - 1098-2760 .- 0895-2477. ; 50:2, s. 416-419
-
Tidskriftsartikel (refereegranskat)abstract
- A novel dielectric catadioptric lens, suitable for near-field sensing and imaging, is presented. The focusing property and the far-field pattern of the lens are investigated using a 3D full-wave electromagnetic solver. Furthermore, the proposed catadioptric lens has been designed and fabricated from Delrin. Simulations and measurements of the far-field at 5 GHz and return loss versus frequency using a Bow-tie slot feeding antenna are presented.
|
|
| 7. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
Catadioptric Dielectric Lens for Imaging Applications
- 2008
-
Ingår i: Proceedings of 33rd International Conference on Infrared, Millimeter, and Terahertz Waves. - 9781424421190 ; , s. 1 - 2
-
Konferensbidrag (refereegranskat)abstract
- The design and characterization results of a novel catadioptric dielectric lens are presented. Although being electrically small, the lens provides a focus in the close vicinity which makes it suitable to be used in microwave and terahertz systems. Several lenses of different dielectric materials and dimensions have been fabricated. A simple backscattering measurement method has been implemented in order to determine the focusing property of the lens.
|
|
| 8. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
Design of Antenna Integrated Photomixers and Catadioptric Lenses for Emerging THz Applications
- 2008
-
Ingår i: 2008 ANSYS Regional Conference.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We will present design and modeling of antenna integrated photomixers for terahertz generation. In addition, the design and the quasioptical integration a novel catadioptric dielectric lens, suitable for imaging applications, will be presented. Although having a tremendous potential, the terahertz (0.1 – 10 THz) regime in the frequency spectrum and its applications are hindered due to the lack of viable and high power terahertz sources. This has led to the term “terahertz gap” being coined. We aim to construct compact sources utilizing the lens-coupled antenna-integrated photomixer sources based on Uni-Travelling-Carrier Photomixers (UTC-PD). These sources are one of the key components which could significantly bridge the terahertz gap.However, optimization of the epitaxial layer structure of the UTC-PD is necessary for high-power THz generation. The epilayers of the UTC-PD is designed and optimized in TCAD. Antennas are designed using HFSS while the impedance of the antenna at a specific bandwidth from HFSS is used to optimize the UTC-PD epilayers and vice versa. Thus proper impedance match and therefore high power THz generation is possible.A novel catadioptric dielectric lens is designed and characterized using HFSS. The lens provides an alternative solution to be used as a focusing element and therefore suitable for imaging or similar applications.In fine, we aim to combine the photomixer source and the lens in order to attain compact but powerful THz sources.
|
|
| 9. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
Development and Design of a 340 GHz Photomixer Source
- 2007
-
Ingår i: 18th International Symposium on Space THz Technology – ISSTT 2007.
-
Konferensbidrag (refereegranskat)abstract
- We present the design of an InGaAlAs/InP uni-traveling-carrier photo-diode (UTC-PD) at mm-wave frequencies up to 340 GHz. The photo diode epitaxy is optimized using a quasi-3D software implementing the hydrodynamic semiconductor equations, for which an output power of 3 mW at 340 GHz was simulated. An equivalent circuit of the UTC-PD has been fitted to experimental S11 measurements up to 67 GHz. Finally, an optimized antenna coupled UTC-PD with choke filter has been designed. This MMIC circuit is intended for photomixing, with output power at 340 GHz.
|
|
| 10. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
High Power Photonic MW/THz Generation Using UTC-PD
- 2008
-
Ingår i: GigaHertz SympoSium 2008. ; , s. 45-
-
Konferensbidrag (refereegranskat)abstract
- The ongoing research work concentrates on extending the previously accomplished UTC-PD fabrication and modelling techniques to 340 GHz and above. We have fabricated and characterized UTC-PDs intended for high power MW/THz generation. Several integrated antenna-detector circuits have been designed and characterised.
|
|
