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ABSTRACT: A novel triple-mode bandpass filter using an open-loop slotline resonator in a defected ground waveguide is presented. Distinct characteristics of the triple-mode resonator are investigated by using even-odd mode analysis. The proposed filter has been designed, fabricated and measured. Good agreement between simulation and measurement verifies the validity of this design methodology.
Electronics Letters 04/2011; · 0.96 Impact Factor
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ABSTRACT: A compact dual-band bandpass filter using side-coupled octagonal split-ring resonators (SRR) is introduced in this letter. The proposed filter employs two sets of SRRs operating at different frequencies to generate two passbands. Besides, the side-coupled stubs provide sufficient degrees of freedom to control the bandwidth of the two passbands. Four transmission zeros can be created close to passband edges which leads to high skirt selectivity. Measured results are in good agreement with the EM simulation results. The circuit size of the proposed filter occupies only 22.4 × 12.6 mm2 (≈0.25 × 0.14 λg). © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1169–1171, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25938
Microwave and Optical Technology Letters 03/2011; 53(5):1169 - 1171. · 0.62 Impact Factor
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B.B. Hong,
L. Choi,
Y.C. Jung,
S.W. Hwang,
K.H. Cho,
K.H. Yeo,
D. Kim,
G.Y. Jin,
D. Park,
S.H. Song,
Y.Y. Lee,
M.H. Son, D. Ahn
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ABSTRACT: We report the random telegraph noise observed in gate-all-around (GAA) PMOS silicon nanowire FETs (SNWFETs) with the radius of 5 nm, at various temperatures (s) down to 4.2 K. From the -dependence of the capture/emission time, we obtain the energy and the charging status of the trap states. The gate bias dependence and the -dependence of the scattering coefficient-mobility product extracted from the relative fluctuation amplitude of the drain current are consistent with the fact that the surface roughness scattering is dominant in GAA PMOS SNWFETs.
IEEE Transactions on Nanotechnology 12/2010; · 2.29 Impact Factor
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ABSTRACT: A modified defected microstrip structure (DMS) for designing a dual-band bandpass filter with independently controlled centre frequencies is presented. The DMS using an F-shaped spurline embedded into a uniform impedance resonator is applied to generate double-resonance characteristics. Based on this theory, a dual-band filter for GPS/WLAN applications has been designed, analysed and fabricated. It is compact and has easy fabrication. Measured results verify the validity of this design methodology. Also, this is believed to be the first report on the DMS in microwave dual-band filter design.
Electronics Letters 11/2010; · 0.96 Impact Factor
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ABSTRACT: A novel dual-mode dual-band bandpass filter (BPF) design using a defected ground waveguide (DGW) with independently controlled centre frequencies is presented. This BPF consists of simple microstrip feedlines and embedded DGW resonators for single substrate configuration. Defected corner cut perturbation is applied to improve out-of-band performance and operating band selectivity. This filter has been designed, fabricated and measured. Good agreement between simulation and measurement verifies the validity of this design methodology.
Electronics Letters 07/2010; · 0.96 Impact Factor
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B H Hong,
L Choi,
Y C Jung,
S W Hwang,
K H Cho,
K H Yeo,
D.-W Kim,
G Y Jin,
D Park,
S H Song,
Y Y Lee,
M H Son, D Ahn
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ABSTRACT: We report the random telegraph noise observed in gate-all-around (GAA) PMOS silicon nanowire FETs (SNWFETs) with the radius of 5 nm, at various temperatures (T s) down to 4.2 K. From the T -dependence of the capture/emission time, we obtain the energy and the charging status of the trap states. The gate bias dependence and the T -dependence of the scattering coefficient-mobility product extracted from the relative fluctuation amplitude of the drain current are consistent with the fact that the surface roughness scattering is dominant in GAA PMOS SNWFETs. Index Terms—Gate all around (GAA), random telegraph noise (RTN), silicon nanowire FET (SNWFET), temperature dependence.
IEEE Transactions on Nanotechnology 01/2010; 9. · 2.29 Impact Factor
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ABSTRACT: We reported the fabrication and characterization of a new type of silicon-on-insulator (SOI) single-electron transistor utilizing usual CMOS sidewall gate structures. We used oxide sidewall spacer layers as well as two poly-Si finger gates on an SOI wire mesa as implantation masks, to form tunnel barriers and thus a quantum dot (QD) that is smaller than the spacing between polygates. Characterization results exhibited clear Coulomb oscillations persisting up to 30 K. The Coulomb energy and the size of the QD extracted from three devices were consistent with the spacing between two poly-Si gates of each device. Furthermore, the junction capacitance of each device was almost constant and only the gate capacitance varied. These analyses suggested that the size of the QD was fully controlled by the process.
IEEE Transactions on Nanotechnology 10/2008; · 2.29 Impact Factor
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K. H. Cho,
Y. C. Jung,
B. H. Hong,
S. W. Hwang,
J. H. Oh, D. Ahn,
S. D. Suk,
K. H. Yeo,
D.-W. Kim,
D. Park,
W.-S. Lee
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ABSTRACT: The authors have measured addition energy spectra from gate-all-around twin silicon nanowire single electron transistors (SETs) with the radius of 5 nm and with circular cross sections. Nonmonotonically varying addition energies are observed and the authors interpret them as shell fillings of silicon nanowire quantum dots with three-dimensional harmonic confinement potentials. A 45 nm long SET shows 2-1-2-1 filling behavior while a 38 nm long SET exhibits 1-2-2-1 filling. These filling behaviors match with the calculated degeneracies of nanowires with different confinement strengths.
Applied Physics Letters 04/2007; 90(18):182102-182102-3. · 3.84 Impact Factor
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J.F. Liu, D. Ahn,
C. Y. Hong,
D. Pan,
S. Jongthammanurak,
M. Beals,
L. C. Kimerling,
J. Michel,
A. T. Pomerene,
D. Carothers,
C. Hill,
M. Jaso,
K. Y. Tu,
Y. K. Chen,
S. Patel,
M. Rasras,
D. M. Gill,
A. E. White
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ABSTRACT: We present selectively grown Ge p-i-n photodetectors coupled to high index contrast Si(core)/SiO<sub>2</sub>(cladding) waveguides on a silicon-on-insulator (SOI) platform. Two coupling schemes, namely butt-coupling and vertical coupling, were demonstrated in this study. With the butt-coupling scheme we have achieved a high responsivity of 1.0 A/W at 1520 nm and a 3 dB bandwidth greater than 4.5 GHz at 1550 nm. With the vertical coupling scheme, where the light couples from a Si waveguide evanescently to the Ge detector on top of it, a responsivity of 0.22 A/W and a 3 dB bandwidth of ~1.5 GHz have been demonstrated at 1550 nm. The devices were fabricated on a standard 180 nm industrial complementary metal oxide semiconductor production (CMOS) line, and can be integrated with CMOS circuitry for electronic and photonic integrated circuits
Optoelectronics, 2006 Optics Valley of China International Symposium on; 12/2006
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ABSTRACT: We demonstrate the fabrication and characterization of single electron transistors composed of Au nanoparticles and insulating molecular tunnel barriers. We fabricated these devices by forming a 1,8-octanedithiol self-assembled monolayer on Au nanogap electrode pairs and by bridging them with colloidal Au nanoparticles using ac dielectrophoresis. We observed the typical characteristics of these single electron transistors at the temperature from 4.2 to 300 K. The measured data were consistent with the orthodox theory of Coulomb blockade.
Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society 02/2006; · 1.34 Impact Factor
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ABSTRACT: In the paper, a regime, where the independent treatment of single-electron transistors (SETs) in transient simulations is valid, has been identified quantitatively. It is found that, as in the steady-state case, although the temperature varies, each SET can be treated independently, even in the transient case when the interconnection capacitance is large enough. However, the value of the load capacitance C<sub>L</sub> of the interconnections for the independent treatment of SETs is approximately ten times larger than that of the steady-state case. A compact SET transient model is developed for transient circuit simulation by SPICE. The developed model is based on a linearised equivalent circuit and the solution of a master equation is done by the programming capabilities of the SmartSpice. Exact delineation of several simulation time scales and the physics-based compact model make it possible to accurately simulate hybrid circuits in the timescales down to several tens of picoseconds.
IEE Proceedings - Circuits Devices and Systems 01/2006; · 0.36 Impact Factor
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ABSTRACT: We report the observation of a unique example of double-dot transport in a silicon-on-insulator nanowire transistor. The transport at low temperature showed typical characteristics of two parallel quantum dots, and anomalous secondary minima were also observed in the dI<sub>D</sub>/dV<sub> DS </sub> spectrum. Our transport data, including these secondary minima, were consistent with two parallel quantum dots, each formed at the front and at the back interface.
Applied Physics Letters 02/2005; · 3.84 Impact Factor
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ABSTRACT: A new defected ground structure (DGS) for the microstrip line is
proposed in this paper. The proposed DGS unit structure can provide the
bandgap characteristic in some frequency bands with only one or more
unit lattices. The equivalent circuit for the proposed defected ground
unit structure is derived by means of three-dimensional field analysis
methods. The equivalent-circuit parameters are extracted by using a
simple circuit analysis method. By employing the extracted parameters
and circuit analysis theory, the bandgap effect for the provided
defected ground unit structure can be explained. By using the derived
and extracted equivalent circuit and parameters, the low-pass filters
are designed and implemented. The experimental results show excellent
agreement with theoretical results and the validity of the modeling
method for the proposed defected ground unit structure
IEEE Transactions on Microwave Theory and Techniques 02/2001; · 1.85 Impact Factor
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ABSTRACT: In this paper, a new design method of band pass filters which have
improved stop band characteristics, using closed loop resonator and
coupled lines, is presented. The stepped impedance line has been used in
resonator structure for improving the performance and reducing physical
size of band pass filters. The connections between in/output ports and
resonator has been realized with microstrip coupled lines. In order to
show the excellence of design method presented here, we have designed
and fabricated a 2-pole band pass filter with a 25-mil-thick microstrip
substrate (ε<sub>r</sub>=10.2) at 1.885~1.905 frequency bands. The
measured results are in good agreement with the simulated performances
Microwave Symposium Digest, 1996., IEEE MTT-S International; 07/1996
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ABSTRACT: Linear gain, gain suppression, and L‐I characteristics of strained‐layer InGaAs/GaAs quantum‐well laser are studied theoretically, taking into account valence‐band mixing effects with biaxial compressive strain. It is found that the biaxial compressive strain substantially alters subband structure by pushing the light‐hold subband bands into higher‐energy states. It also alters the optical gain of a quantum‐well laser. In particular, the biaxially compressed strained‐layer InGaAs/GaAs quantum well shows a pronounced preference for TE polarization over TM polarization and the higher optical gain than does a typical GaAs/AlGaAs quantum well. The L‐I characteristics are obtained self‐consistently from the rate equations for the carrier and the photon densities and the calculated L‐I curve shows reasonable agreement with the experimental data.
Applied Physics Letters 03/1992; · 3.84 Impact Factor
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ABSTRACT: Polarization‐dependent optical gain of recently demonstrated CdZnSe/ZnSe quantum well lasers is calculated for the first time. Our analysis is based on the multiband effective mass theory (k∙p theory) and the density matrix formalism with intraband relaxation taken into account. It is shown theoretically that the TE mode gain is significantly larger than the TM mode gain for a wide range of carrier density. Comparison of the room‐temperature TE mode gain of CdZnSe/ZnSe quantum well with that of GaAs/AlGaAs quantum well gives disappointing results for the II‐VI semiconductor lasers. It is expected that the optical gain of the ZnSe‐based semiconductor lasers would be substantially smaller than the optical gain of the GaAs‐based semiconductor lasers for a same quantum well width and carrier density.
Applied Physics Letters 12/1991; · 3.84 Impact Factor
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ABSTRACT: The effects of various structure parameters such as graded potential, strain, quantum‐well size, barrier heights, and temperature on the optical gain of single quantum‐well lasers are studied for a potential solution to the problem of device optimization from the unified point of view with a rigorous model for gain. This study on the structure parameter dependence of the gain with the valence band mixing as well as intraband relaxation is new and presents a unified scheme for the optical gain control. Significant enhancement of gain in the graded quantum well as compared with that of the ordinary square quantum well is predicted. With the uniaxial stress, the TE mode gain is suppressed while the TM mode gain is enhanced due to the change of valence band structure. Calculated results show that the roles played by structure parameters such as well width, barrier heights, and temperature on the optical gain becomes of great importance for the device optimization.
Journal of Applied Physics 12/1991; · 2.17 Impact Factor
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ABSTRACT: Both interband and intersubband optical transitions in a parabolic quantum well with an applied electric field are investigated. The wave functions for the electrons and holes are those of the displaced harmonic oscillators, which are shifted in opposite directions. The dipole moment matrices, the absorption coefficients, and the changes in the refractive indices are evaluated with the intrasubband relaxations taken into account. Interesting electroabsorption and electro‐optic effects are presented analytically and numerically.
Journal of Applied Physics 05/1989; · 2.17 Impact Factor
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ABSTRACT: The effects of free‐carrier screening and valence band mixing on gain‐switching characteristics of the field‐effect quantum‐well laser are studied theoretically. Our analysis is based on the multiband effective mass theory and the density matrix formalism with the intraband relaxation taken into account. We calculate the electronic structure of the quantum well by solving simultaneously the multiband effective mass equations for the envelope functions with Poisson’s equation. It is found that the free‐carrier screening affects considerably both electronic properties (band structure and wave functions) and gain‐switching characteristics by reducing the electric field and charge separation in the quantum well when the gate field is applied across the quantum well.
Journal of Applied Physics 01/1989; · 2.17 Impact Factor
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ABSTRACT: The effects of valence‐band mixing on the gain and on the refractive index change of the quantum‐well laser and the effect of an applied electric field perpendicular to the quantum wells for gain switching are studied theoretically. Our calculations are based on the multiband effective‐mass theory (k∙p method) and the density‐matrix formalism with the intraband relaxation taken into account. First, we calculate the nonparabolic valence‐band structure by the finite difference method after making a unitary transformation of the Luttinger‐Kohn Hamiltonian. The calculated gain for our model shows remarkable differences in both spectral shape and peak amplitude as compared with those for the conventional model of the parabolic valence band. The peak gain is reduced considerably and the gain spectrum is more symmetric in our model compared with that for the conventional model. The refractive index change shows a negative increment in the active region for both the TE and TM polarizations resulting in the antiguidance. However, the TM polarization shows more negative change which would result in the suppression of the TM modes as compared with the TE modes. As another example, the perpendicular electric field effects on the quantum‐well laser with lateral current injection are also calculated. A red shift and a reduction of the gain spectrum are shown when an electric field is applied. This may have applications as a tunable and high‐speed switching quantum‐well laser.
Journal of Applied Physics 11/1988; · 2.17 Impact Factor
