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Abstract The authors report a novel approach for designing tunable and reconfigurable bandstop filters by employing bias‐free optically‐controlled photoconductive radio frequency (RF) switching elements. To verify the effectiveness of the approach, a bandstop filter with two stopbands centred at 4.05 and 4.75 GHz was designed using a split‐ring‐coupled microstrip transmission line on RO3010 substrates. To enable reconfigurability, a micromachined Si chip with a thickness of ∼73 μm was embedded in the gap of each resonator. The tuning and reconfiguring of the filter are accomplished by selectively illuminating the Si chips using fibre‐coupled laser diodes with a wavelength of 808 nm. By turning on and off each laser diode, the filter stop bands can be dynamically reconfigured. In addition, the suppression of each stop band can be continuously and independently tuned by changing the light intensity from 0 to 20 W/cm2. With geometric scaling, this approach is promising for realizing a novel class of compact and high‐performance tunable and/or reconfigurable circuits from the microwave to mmW‐THz region.
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Omega‐Gate Silicon Nanowire Geometric Diodes with Reconfigurable Self‐Switching Operation and THz Rectification
Abstract Geometric diodes (GDs) represent a relatively unconventional class of diode that produces an asymmetric current response through carrier transport in an asymmetric geometry. Synthesized from the bottom up, Si nanowire‐based GDs are three‐dimensional, cylindrically symmetric nanoscale versions capable of room‐temperature rectification at GHz‐THz frequencies with near zero‐bias turn‐on voltages. Here, by fabricating three‐terminal n‐type Si nanowire GDs with axial contacts and an omega‐gate electrode, a distinct class of reconfigurable self‐switching geometric diodes (SSGDs) is reported. Single‐nanowire SSGD device measurements demonstrate a significant dependence of diode current and polarity on gate potential, where the diode polarity reverses at a gate potential of ≈−1 V under specific grounding conditions. Finite‐element modeling reproduces the experimental results and reveals that the gate potential—in combination with the morphology and dopant profile—produces an asymmetric potential along the nanowire axis that changes asymmetrically with axial bias, altering the effective conductive channel within the nanowire to yield diode behavior. The self‐switching effect is retained in two‐terminal SSGD devices, and modeling demonstrates that both three‐terminal and two‐terminal devices support rectification through THz frequencies. The results reveal a new mechanism of operation for nanowire‐based GDs and characterize a new type of self‐switching diode with reconfigurable polarity.
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- PAR ID:
- 10469378
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Electronic Materials
- Volume:
- 10
- Issue:
- 1
- ISSN:
- 2199-160X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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