Emerging Functions of Nanostructured Porous Silicon—With a Focus on the Emissive Properties of Photons, Electrons, and Ultrasound
Recent topics of application studies on porous silicon (PS) are reviewed here with a focus on the emissive properties of visible light, quasiballistic hot electrons, and acoustic wave. By exposing PS in solvents to pulse laser, size-controlled nc-Si dot colloids can be formed through fragmentation o...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2019-04-01
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| Series: | Frontiers in Chemistry |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fchem.2019.00273/full |
| _version_ | 1819157257405857792 |
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| author | Nobuyoshi Koshida Toshihiro Nakamura |
| author_facet | Nobuyoshi Koshida Toshihiro Nakamura |
| author_sort | Nobuyoshi Koshida |
| collection | DOAJ |
| description | Recent topics of application studies on porous silicon (PS) are reviewed here with a focus on the emissive properties of visible light, quasiballistic hot electrons, and acoustic wave. By exposing PS in solvents to pulse laser, size-controlled nc-Si dot colloids can be formed through fragmentation of the PS layer with a considerably higher yield than the conventional techniques such as laser ablation of bulk silicon and sol-gel precursor process. Fabricated colloidal samples show strong visible photoluminescence (~40% in quantum efficiency in the red band). This provides an energy- and cost-effective route for production of nc-Si quantum dots. A multiple-tunneling transport mode through nc-Si dot chain induces efficient quasiballistic hot electron emission from an nc-Si diode. Both the efficiency and the output electron energy dispersion are remarkably improved by using monolayer graphene as a surface electrode. Being a relatively low operating voltage device compatible with silicon planar fabrication process, the emitter is applicable to mask-less parallel lithography under an active matrix drive. It has been demonstrated that the integrated 100 × 100 emitter array is useful for multibeam lithography and that the selected emission pattern is delineated with little distortion. Highly reducing activity of emitted electrons is applicable to liquid-phase thin film deposition of metals (Cu) and semiconductors (Si, Ge, and SiGe). Due to an extremely low thermal conductivity and volumetric heat capacity of nc-Si layer, on the other hand, thermo-acoustic conversion is enhanced to a practical level. A temperature fluctuation produced at the surface of nc-Si layer is quickly transferred into air, and then an acoustic wave is emitted without any mechanical vibrations. The non-resonant and broad-band emissivity with low harmonic distortions makes it possible to use the emitter for generating audible sound under a full digital drive and reproducing complicated ultrasonic communication calls between mice. |
| first_indexed | 2024-12-22T16:05:49Z |
| format | Article |
| id | doaj.art-d25914b240594666be011392a8094240 |
| institution | Directory Open Access Journal |
| issn | 2296-2646 |
| language | English |
| last_indexed | 2024-12-22T16:05:49Z |
| publishDate | 2019-04-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Chemistry |
| spelling | doaj.art-d25914b240594666be011392a80942402022-12-21T18:20:36ZengFrontiers Media S.A.Frontiers in Chemistry2296-26462019-04-01710.3389/fchem.2019.00273448359Emerging Functions of Nanostructured Porous Silicon—With a Focus on the Emissive Properties of Photons, Electrons, and UltrasoundNobuyoshi Koshida0Toshihiro Nakamura1Graduate School of Engineering, Tokyo University of Agriculture and Technology, Fuchu, JapanDepartment of Electrical and Electronic Engineering, Hosei University, Tokyo, JapanRecent topics of application studies on porous silicon (PS) are reviewed here with a focus on the emissive properties of visible light, quasiballistic hot electrons, and acoustic wave. By exposing PS in solvents to pulse laser, size-controlled nc-Si dot colloids can be formed through fragmentation of the PS layer with a considerably higher yield than the conventional techniques such as laser ablation of bulk silicon and sol-gel precursor process. Fabricated colloidal samples show strong visible photoluminescence (~40% in quantum efficiency in the red band). This provides an energy- and cost-effective route for production of nc-Si quantum dots. A multiple-tunneling transport mode through nc-Si dot chain induces efficient quasiballistic hot electron emission from an nc-Si diode. Both the efficiency and the output electron energy dispersion are remarkably improved by using monolayer graphene as a surface electrode. Being a relatively low operating voltage device compatible with silicon planar fabrication process, the emitter is applicable to mask-less parallel lithography under an active matrix drive. It has been demonstrated that the integrated 100 × 100 emitter array is useful for multibeam lithography and that the selected emission pattern is delineated with little distortion. Highly reducing activity of emitted electrons is applicable to liquid-phase thin film deposition of metals (Cu) and semiconductors (Si, Ge, and SiGe). Due to an extremely low thermal conductivity and volumetric heat capacity of nc-Si layer, on the other hand, thermo-acoustic conversion is enhanced to a practical level. A temperature fluctuation produced at the surface of nc-Si layer is quickly transferred into air, and then an acoustic wave is emitted without any mechanical vibrations. The non-resonant and broad-band emissivity with low harmonic distortions makes it possible to use the emitter for generating audible sound under a full digital drive and reproducing complicated ultrasonic communication calls between mice.https://www.frontiersin.org/article/10.3389/fchem.2019.00273/fullporous siliconnanocrystalcolloidal siliconphotoluminescenceballistic electron emissionthermoacoustic |
| spellingShingle | Nobuyoshi Koshida Toshihiro Nakamura Emerging Functions of Nanostructured Porous Silicon—With a Focus on the Emissive Properties of Photons, Electrons, and Ultrasound Frontiers in Chemistry porous silicon nanocrystal colloidal silicon photoluminescence ballistic electron emission thermoacoustic |
| title | Emerging Functions of Nanostructured Porous Silicon—With a Focus on the Emissive Properties of Photons, Electrons, and Ultrasound |
| title_full | Emerging Functions of Nanostructured Porous Silicon—With a Focus on the Emissive Properties of Photons, Electrons, and Ultrasound |
| title_fullStr | Emerging Functions of Nanostructured Porous Silicon—With a Focus on the Emissive Properties of Photons, Electrons, and Ultrasound |
| title_full_unstemmed | Emerging Functions of Nanostructured Porous Silicon—With a Focus on the Emissive Properties of Photons, Electrons, and Ultrasound |
| title_short | Emerging Functions of Nanostructured Porous Silicon—With a Focus on the Emissive Properties of Photons, Electrons, and Ultrasound |
| title_sort | emerging functions of nanostructured porous silicon with a focus on the emissive properties of photons electrons and ultrasound |
| topic | porous silicon nanocrystal colloidal silicon photoluminescence ballistic electron emission thermoacoustic |
| url | https://www.frontiersin.org/article/10.3389/fchem.2019.00273/full |
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