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December 10, 2024
Advancing Energy Conversion: Hybrid Metal-Dielectric Emitters for Thermophotovoltaic Systems
Advancing Energy Conversion: Hybrid Metal-Dielectric Emitters for Thermophotovoltaic Systems
A recent study in NPJ | Nanophotonics unveiled a cutting-edge hybrid metal-dielectric non-Hermitian emitter (NHE) designed to enhance thermophotovoltaic (TPV) system efficiency. This innovative emitter, tailored for low- and mid-grade heat sources, demonstrates superior spectral efficiency and thermal stability, addressing critical challenges in waste heat recovery and renewable energy applications.
Key to the NHE's design is its integration of metallic and dielectric materials. Tungsten serves as both a heat exchanger and a plasmonic substrate, while a dielectric silica spacer and cylindrical silicon resonators enable precise spectral emission. The fabrication process, leveraging planar nanofabrication techniques like plasma-enhanced chemical vapor deposition (PECVD) and electron-beam lithography, was pivotal in achieving this breakthrough. PECVD was essential for producing the silica spacer with precise thickness, ensuring optimal coupling between resonator modes and enhancing spectral selectivity.
The researchers demonstrated the NHE’s efficacy with a spectral efficiency exceeding 60% and remarkable thermal stability at 1273 K, surpassing traditional emitters. Notably, the hybrid structure achieved over 300% higher efficiency than blackbody emitters across specific bandgap energy ranges. When integrated with gallium antimonide (GaSb) photovoltaic cells, the NHE produced a power output of 10.8 mW at 1173 K, showcasing its potential for energy conversion applications.
By enhancing photon management and thermal stability, this NHE design paves the way for improved TPV systems. These advancements underscore the importance of precise material engineering, such as vapor deposition techniques, in driving innovation for sustainable energy solutions and waste heat recovery. Learn more about this topic here.
Key to the NHE's design is its integration of metallic and dielectric materials. Tungsten serves as both a heat exchanger and a plasmonic substrate, while a dielectric silica spacer and cylindrical silicon resonators enable precise spectral emission. The fabrication process, leveraging planar nanofabrication techniques like plasma-enhanced chemical vapor deposition (PECVD) and electron-beam lithography, was pivotal in achieving this breakthrough. PECVD was essential for producing the silica spacer with precise thickness, ensuring optimal coupling between resonator modes and enhancing spectral selectivity.
The researchers demonstrated the NHE’s efficacy with a spectral efficiency exceeding 60% and remarkable thermal stability at 1273 K, surpassing traditional emitters. Notably, the hybrid structure achieved over 300% higher efficiency than blackbody emitters across specific bandgap energy ranges. When integrated with gallium antimonide (GaSb) photovoltaic cells, the NHE produced a power output of 10.8 mW at 1173 K, showcasing its potential for energy conversion applications.
By enhancing photon management and thermal stability, this NHE design paves the way for improved TPV systems. These advancements underscore the importance of precise material engineering, such as vapor deposition techniques, in driving innovation for sustainable energy solutions and waste heat recovery. Learn more about this topic here.
December 23, 2024
High-Performance FBAR Filters for Enhanced WLAN Applications
High-Performance FBAR Filters for Enhanced WLAN Applications
Wireless Local Area Networks (WLAN) have become indispensable in modern connectivity, driving the demand for higher efficiency, stability, and responsiveness. Central to meeting these requirements are high-performance filters, which rely on Film Bulk Acoustic Resonators (FBARs) for their exceptional quality factor (Q) and low loss characteristics.
Traditional air-gap type FBARs face limitations in advancing to higher frequencies above 5 GHz due to poor crystallinity in aluminum nitride (AlN) deposited on sacrificial layers. While single-crystal AlN offers improvements, its high internal stress and complex fabrication processes hinder scalability. To address these challenges, this study explores the design and fabrication of FBARs optimized for WLAN applications using vacuum deposition techniques.
The process begins with the deposition of an AlN seed layer and a 280 nm-thick Al0.8Sc0.2N film onto a silicon substrate via physical vapor deposition (PVD). This innovative approach achieves a high-quality Al0.8Sc0.2N film with a full width at half maximum (FWHM) of just 2.1°. Subsequently, the ultra-thin film is transferred to another silicon substrate using wafer bonding, flipping, and silicon removal. This integration with conventional manufacturing processes enables the creation of FBARs with a resonant frequency of 5.5 GHz, an effective electromechanical coupling coefficient (κ) of 13.8%, and an impressive figure of merit (FOM) of 85.
A lattice-type filter based on these FBARs further enhances WLAN performance, featuring a center frequency of 5.5 GHz and a −3 dB bandwidth of 306 MHz. This innovative development supports high data rates and large throughputs, making it a significant step forward in WLAN filter technology. Learn more about this study here.
Traditional air-gap type FBARs face limitations in advancing to higher frequencies above 5 GHz due to poor crystallinity in aluminum nitride (AlN) deposited on sacrificial layers. While single-crystal AlN offers improvements, its high internal stress and complex fabrication processes hinder scalability. To address these challenges, this study explores the design and fabrication of FBARs optimized for WLAN applications using vacuum deposition techniques.
The process begins with the deposition of an AlN seed layer and a 280 nm-thick Al0.8Sc0.2N film onto a silicon substrate via physical vapor deposition (PVD). This innovative approach achieves a high-quality Al0.8Sc0.2N film with a full width at half maximum (FWHM) of just 2.1°. Subsequently, the ultra-thin film is transferred to another silicon substrate using wafer bonding, flipping, and silicon removal. This integration with conventional manufacturing processes enables the creation of FBARs with a resonant frequency of 5.5 GHz, an effective electromechanical coupling coefficient (κ) of 13.8%, and an impressive figure of merit (FOM) of 85.
A lattice-type filter based on these FBARs further enhances WLAN performance, featuring a center frequency of 5.5 GHz and a −3 dB bandwidth of 306 MHz. This innovative development supports high data rates and large throughputs, making it a significant step forward in WLAN filter technology. Learn more about this study here.
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