Graphene is an alternative material for photodetectors owing to its unique properties.These include its uniform absorption of light from ultraviolet to infrared and its ultrahigh mobility for both electrons and holes....Graphene is an alternative material for photodetectors owing to its unique properties.These include its uniform absorption of light from ultraviolet to infrared and its ultrahigh mobility for both electrons and holes.Unfortunately,due to the low absorption of light,the photoresponsivity of graphene-based photodetectors is usually low,only a few milliamps per watt.In this letter,we fabricate a waveguide-integrated graphene photodetector.A photoresponsivity exceeding0.11 A·W （-1） is obtained which enables most optoelectronic applications.The dominating mechanism of photoresponse is investigated and is attributed to the photo-induced bolometric effect.Theoretical calculation shows that the bolometric photoresponsivity is 4.6 A·W （-1）.The absorption coefficient of the device is estimated to be 0.27 dB·μm （-1）.展开更多
We preform first-principle calculations for the geometric, electronic structures and optical properties of SiC nanowires（NWs）. The dielectric functions dominated by electronic interband transitions are investigated ...We preform first-principle calculations for the geometric, electronic structures and optical properties of SiC nanowires（NWs）. The dielectric functions dominated by electronic interband transitions are investigated in terms of the calculated optical response functions. The calculated results reveal that the SiC NW is an indirect band-gap semiconductor material except at a minimum SiC NW（n = 12） diameter, showing that the NW（n = 12） is metallic. Charge density indicates that the Si–C bond of SiC NW has mixed ionic and covalent characteristics： the covalent character is stronger than the ionic character, and shows strong s–p hybrid orbit characteristics. Moreover, the band gap increases as the SiC NW diameter increases. This shows a significant quantum size and surface effect. The optical properties indicate that the obvious dielectric absorption peaks shift towards the high energy, and that there is a blue shift phenomenon in the ultraviolet region. These results show that SiC NW is a promising optoelectronic material for the potential applications in ultraviolet photoelectron devices.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0402204)the High-Tech Research and Development Program of China(Grant Nos.2013AA031401,2015AA016902,and 2015AA016904)the National Natural Science Foundation of China(Grant Nos.61674136,61176053,61274069,and 61435002)
文摘Graphene is an alternative material for photodetectors owing to its unique properties.These include its uniform absorption of light from ultraviolet to infrared and its ultrahigh mobility for both electrons and holes.Unfortunately,due to the low absorption of light,the photoresponsivity of graphene-based photodetectors is usually low,only a few milliamps per watt.In this letter,we fabricate a waveguide-integrated graphene photodetector.A photoresponsivity exceeding0.11 A·W （-1） is obtained which enables most optoelectronic applications.The dominating mechanism of photoresponse is investigated and is attributed to the photo-induced bolometric effect.Theoretical calculation shows that the bolometric photoresponsivity is 4.6 A·W （-1）.The absorption coefficient of the device is estimated to be 0.27 dB·μm （-1）.
基金Project supported by the National Natural Science Foundation of China(Grant No.61664008)the Special Research Funds for Discipline Construction of High Level University Project,China(Grant No.2015SXTS02)the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(Grant Nos.2015R1D1A1A01058991 and 2016R1A6A1A03012877)
文摘We preform first-principle calculations for the geometric, electronic structures and optical properties of SiC nanowires（NWs）. The dielectric functions dominated by electronic interband transitions are investigated in terms of the calculated optical response functions. The calculated results reveal that the SiC NW is an indirect band-gap semiconductor material except at a minimum SiC NW（n = 12） diameter, showing that the NW（n = 12） is metallic. Charge density indicates that the Si–C bond of SiC NW has mixed ionic and covalent characteristics： the covalent character is stronger than the ionic character, and shows strong s–p hybrid orbit characteristics. Moreover, the band gap increases as the SiC NW diameter increases. This shows a significant quantum size and surface effect. The optical properties indicate that the obvious dielectric absorption peaks shift towards the high energy, and that there is a blue shift phenomenon in the ultraviolet region. These results show that SiC NW is a promising optoelectronic material for the potential applications in ultraviolet photoelectron devices.
