| 1. |
- Nie, Liying, et al.
(författare)
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A low-profile wideband dual-resonance tri-port MIMO antenna
- 2022
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 70:6, s. 4866-4871
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Tidskriftsartikel (refereegranskat)abstract
- A low-profile wideband tri-polarized MIMO antenna is proposed in this paper. Based on characteristic mode analysis of a circular patch, four slots are etched symmetrically on the patch to transform the high-order monopole-like modes into broadside modes with lower resonant frequencies. Four sets of shorting pins are also applied to simultaneously adjust the resonant frequencies of the monopole-like modes and broadside fundamental modes of the patch. The effects of the slots and the shorting pins on these modes are analyzed in detail. Three dual-resonance ports with high isolation are achieved by exciting three pairs of orthogonal modes of the patch. The proposed antenna is wideband with respect to its profile (bandwidth/height = 216), as facilitated by the dual-resonance property of each port. Experimental results show that the proposed antenna features high port isolation (> 35 dB) and high gain (> 5.58 dB). The proposed low-profile wideband tri-port antenna can be applied in highly integrated MIMO systems.
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| 2. |
- Nie, Liying, et al.
(författare)
-
Wideband design of compact monopole-Like circular patch antenna using modal analysis
- 2021
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 20:6, s. 918-922
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a systematic approach to design a compact dual-mode monopole-like patch antenna using characteristic mode analysis (CMA). The modal analysis of a slotted circular patch structure incorporating a new shorting pin loading technique is presented. To achieve a compact monopole-like antenna with wideband operation, it is demonstrated that the first two significant modes with monopole-like patterns are the most suitable ones for dual-mode excitation. Based on the analysis of the modal currents and electric fields, four groups of shorting pins and four slots are introduced to individually tune the two modes, which facilitates the optimization. The effects of these slots and shorting pins on the resonant frequencies of the two modes are analyzed in detail. Finally, a CPW T-junction power divider is applied to simultaneously excite these two modes and suppress the undesired modes. Apart from a more compact form factor and higher gain than existing work, it also features a competitive gain-bandwidth per volume ratio.
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| 3. |
- Pan, Kui, et al.
(författare)
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Highly effective transfer of micro-LED pixels to the intermediate and rigid substrate with weak and tunable adhesion by thiol modification
- 2023
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 15:9, s. 4420-4428
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Tidskriftsartikel (refereegranskat)abstract
- Based on transfer printing technology, micro-LED pixels can be transferred to different types and sizes of driving substrates to realize displays with different application scenarios. To achieve a successful transfer, GaN-based micro-LEDs first need to be separated from the original epitaxial substrate. Here, micro-LED pixels (each size 25 μm × 30 μm) on the sapphire substrate were transferred to a flexible semiconductor wafer processing (SWP) tape that is strongly sticky by conventional laser lift-off (LLO) techniques. The pixels on the SWP tape were then transferred by using a sacrificial layer of non-crosslinked oligomeric polystyrene (PS) film onto the intermediate and rigid substrate (IRS) with weak and tunable adhesion by thiol (-SH) modification. The electrode of the micro-LED is Au metal, which forms Au-S bonds with the surface of the IRS to fix the pixels. The rigid substrate helps ensure that the pixel spacing is almost unchanged during the stamp transfer process, and the weak and tunable adhesion facilitates the pixels being picked up by the stamp. The experimental results demonstrate that the pixels can be efficiently transferred to the IRS by LLO and sacrificial layer-assistance, which will provide the possibility of achieving the further transfer of pixels to different types and sizes of driving substrates by a suitable transfer stamp. The transfer process details are discussed, which can provide insights into the transfer of micro-nano devices through polymer sacrificial layers.
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| 4. |
- Pan, Kui, et al.
(författare)
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Monolithically and Vertically Integrated LED-on-FET Device Based on a Novel GaN Epitaxial Structure
- 2023
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Ingår i: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 70:12, s. 6393-6398
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Tidskriftsartikel (refereegranskat)abstract
- Optoelectronic devices, such as light-emitting diodes (LEDs), based on GaN-based semiconductor compounds are widely used for their advantages of long life, high reliability, and low energy consumption. The persistent challenge is integrating LED with transistors to achieve smaller size, lighter weight, higher speed, and more reliable optoelectronic integrated circuits. Here, we report monolithically and vertically integrated LED-on-FET devices fabricated on a novel GaN epitaxial structure. The designed device structure and fabrication process are simple. It also eliminates the extra area occupied by the transistor, and the shared n-GaN layer between the LED and FET reduces interconnect resistance and improves reliability. The measured threshold voltage (V-Th) of the LED-on-FET device is extrapolated as 3.9 V at the voltage (V-DD) of 5 V, and V-Th decreases with the increase of V-DD . More importantly, the gate voltage (V-GS) shows good performance in modulated electroluminescence (EL) intensity and switching capability of the LED. The integrated LED efficiently emits light modulation with a wavelength of 440 nm at V-DD= 9 V and V-GS=4-9 V (step = 1 V), which are necessary for devices in applications, such as displays and smart lighting. This epitaxy structure and integration scheme is promising in achieving large-scale optoelectronic integrated circuits, such as the next-generation micro-LED and nano-LED with super compact integrated drivers.
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