Graphene, with its zero-bandgap electronic structure, is a highly promising ultra-broadband light absorbing material.However, the performance of graphene-based photodetectors is limited by weak absorption efficiency a...Graphene, with its zero-bandgap electronic structure, is a highly promising ultra-broadband light absorbing material.However, the performance of graphene-based photodetectors is limited by weak absorption efficiency and rapid recombination of photoexcited carriers, leading to poor photodetection performance. Here, inspired by the photogating effect, we demonstrated a highly sensitive photodetector based on graphene/WSe_(2) vertical heterostructure where the WSe_(2) layer acts as both the light absorption layer and the localized grating layer. The graphene conductive channel is induced to produce more carriers by capacitive coupling. Due to the strong light absorption and high external quantum efficiency of multilayer WSe_(2), as well as the high carrier mobility of graphene, a high photocurrent is generated in the vertical heterostructure. As a result, the photodetector exhibits ultra-high responsivity of 3.85×10~4A/W and external quantum efficiency of 1.3 × 10~7%.This finding demonstrates that photogating structures can effectively enhance the sensitivity of graphene-based photodetectors and may have great potential applications in future optoelectronic devices.展开更多
A Ge/Si（001） island multilayer structure is investigated by double crystal X-ray diffraction, transmission electron microscopy,and atomic force microscopy. We fit the satellite peaks in the rocking curve by two Lore...A Ge/Si（001） island multilayer structure is investigated by double crystal X-ray diffraction, transmission electron microscopy,and atomic force microscopy. We fit the satellite peaks in the rocking curve by two Lorentz lineshapes, which originate from the wetting layer region and the island region. Then from the ratio of the thick- nesses of the Si and Ge （GeSi） layers as determined by TEM,tbe Ge compositions of the wetting layer and islands are estimated to be about 0. 51 and 0. 67, respectively,according to the positions of the fitted peaks. This proves to be a relatively simple way to investigate the Ge/Si （001） island multilayer structure.展开更多
A SiGe/Si multi-quantum wells resonant-cavity-enhanced(RCE) detector with high reflectivity bottom mirror is fabricated by a new method.The bottom mirror is deposited in the hole,which is etched from the backside of t...A SiGe/Si multi-quantum wells resonant-cavity-enhanced(RCE) detector with high reflectivity bottom mirror is fabricated by a new method.The bottom mirror is deposited in the hole,which is etched from the backside of the sample by ethylenediamine-pyrocatechol-water(EPW) solution with the buried SiO 2 layer in SOI substrate as the etching-stop layer.Reflectivity spectrum indicates that the mirror deposited in the hole has a reflectivity as high as 99% in the range of 1.2～1.5μm.The peak responsivity of the RCE detector at 1.344μm is 1.2mA/W and the full width at half maximum is 12nm.Compared with the conventional p-i-n photodetector,the responsivity of RCE detector is enhanced 8 times.展开更多
A large area multi-finger configuration power SiGe HBT device （with an emitter area of about 880μm^2） was fabricated with 2μm double-mesa technology. The maximum DC current gain β is 214. The BVCEO is up to 10V,a...A large area multi-finger configuration power SiGe HBT device （with an emitter area of about 880μm^2） was fabricated with 2μm double-mesa technology. The maximum DC current gain β is 214. The BVCEO is up to 10V,and the BVCBO is up to 16V with a collector doping concentration of 1 × 10^17cm^-3 and collector thickness of 400nm. The device exhibits a maximum oscillation frequency fmax of 19. 3GHz and a cut-off frequency fT of 18.0GHz at a DC bias point of Ic = 30mA and VCE = 3V.MSG （maximum stable gain） is 24.5dB,and U （Mason unilateral gain） is 26.6dB at 1GHz. Due to the novel distribution layout, no notable current gain fall-off or thermal effects are observed in the I-V characteristics at high collector current.展开更多
基金the National Natural Science Foundation of China(60908012,61575008,61775007,61874145,62074011,62134008)National Key Research and Development Program of China(2018YFA0209000,2021YFC2203400,2021YFA1200804)+1 种基金the Beijing Natural Science Foun⁃dation(4172011,4202010)Beijing Nova Program(Z201100006820096)。
基金Project supported by the National Natural Science Foundation of China (Grant No.11974379)the National Key Basic Research and Development Program of China (Grant No.2021YFC2203400)Jiangsu Vocational Education Integrated Circuit Technology “Double-Qualified” Famous Teacher Studio (Grant No.2022-13)。
文摘Graphene, with its zero-bandgap electronic structure, is a highly promising ultra-broadband light absorbing material.However, the performance of graphene-based photodetectors is limited by weak absorption efficiency and rapid recombination of photoexcited carriers, leading to poor photodetection performance. Here, inspired by the photogating effect, we demonstrated a highly sensitive photodetector based on graphene/WSe_(2) vertical heterostructure where the WSe_(2) layer acts as both the light absorption layer and the localized grating layer. The graphene conductive channel is induced to produce more carriers by capacitive coupling. Due to the strong light absorption and high external quantum efficiency of multilayer WSe_(2), as well as the high carrier mobility of graphene, a high photocurrent is generated in the vertical heterostructure. As a result, the photodetector exhibits ultra-high responsivity of 3.85×10~4A/W and external quantum efficiency of 1.3 × 10~7%.This finding demonstrates that photogating structures can effectively enhance the sensitivity of graphene-based photodetectors and may have great potential applications in future optoelectronic devices.
文摘A Ge/Si（001） island multilayer structure is investigated by double crystal X-ray diffraction, transmission electron microscopy,and atomic force microscopy. We fit the satellite peaks in the rocking curve by two Lorentz lineshapes, which originate from the wetting layer region and the island region. Then from the ratio of the thick- nesses of the Si and Ge （GeSi） layers as determined by TEM,tbe Ge compositions of the wetting layer and islands are estimated to be about 0. 51 and 0. 67, respectively,according to the positions of the fitted peaks. This proves to be a relatively simple way to investigate the Ge/Si （001） island multilayer structure.
文摘A SiGe/Si multi-quantum wells resonant-cavity-enhanced(RCE) detector with high reflectivity bottom mirror is fabricated by a new method.The bottom mirror is deposited in the hole,which is etched from the backside of the sample by ethylenediamine-pyrocatechol-water(EPW) solution with the buried SiO 2 layer in SOI substrate as the etching-stop layer.Reflectivity spectrum indicates that the mirror deposited in the hole has a reflectivity as high as 99% in the range of 1.2～1.5μm.The peak responsivity of the RCE detector at 1.344μm is 1.2mA/W and the full width at half maximum is 12nm.Compared with the conventional p-i-n photodetector,the responsivity of RCE detector is enhanced 8 times.
文摘A large area multi-finger configuration power SiGe HBT device （with an emitter area of about 880μm^2） was fabricated with 2μm double-mesa technology. The maximum DC current gain β is 214. The BVCEO is up to 10V,and the BVCBO is up to 16V with a collector doping concentration of 1 × 10^17cm^-3 and collector thickness of 400nm. The device exhibits a maximum oscillation frequency fmax of 19. 3GHz and a cut-off frequency fT of 18.0GHz at a DC bias point of Ic = 30mA and VCE = 3V.MSG （maximum stable gain） is 24.5dB,and U （Mason unilateral gain） is 26.6dB at 1GHz. Due to the novel distribution layout, no notable current gain fall-off or thermal effects are observed in the I-V characteristics at high collector current.
