Aiming to achieve InAs quantum dots(QDs) with a long carrier lifetime,the effects of Sb component in cap layers on the band alignment of the InAs/GaAsSb QDs have been studied.InAs QDs with high density and uniformity ...Aiming to achieve InAs quantum dots(QDs) with a long carrier lifetime,the effects of Sb component in cap layers on the band alignment of the InAs/GaAsSb QDs have been studied.InAs QDs with high density and uniformity have been grown by molecular beam epitaxy.With increasing Sb composition,the InAs/GaAsSb QDs exhibit a significant redshift and broadening photoluminescence(PL).With a high Sb component of 22%,the longest wavelength emission of the InAs/GaAs_(0.78)Sb_(0.22) QDs occurs at 1.5 μm at room temperature.The power-dependence PL measurements indicate that with a low Sb component of 14%,the InAs/GaAs_(0.86)Sb_(0.14) QDs have a type-Ⅰ and a type-Ⅱ carrier recombination processes,respectively.With a high Sb component of 22%,the InAs/GaAs_(0.78)Sb_(0.22) QDs have a pure type-Ⅱ band alignment,with three type-Ⅱ carrier recombination processes.Extracted from time-resolved PL decay traces,the carrier lifetime of the InAs/GaAs_(0.78)Sb_(0.22) QDs reaches 16.86 ns,which is much longer than that of the InAs/GaAs_(0.86)Sb_(0.14) QDs(2.07 ns).These results obtained here are meaningful to realize high conversion efficiency intermediate-band QD solar cells and other opto-electronic device.展开更多
The performance of the photodetector is significantly impacted by the inherent surface faults in GaAs nanowires(NWs).We combined three-dimensional(3D)gallium arsenide nanowires with zero-dimensional(0D)WS_(2) quantum ...The performance of the photodetector is significantly impacted by the inherent surface faults in GaAs nanowires(NWs).We combined three-dimensional(3D)gallium arsenide nanowires with zero-dimensional(0D)WS_(2) quantum dot(QDs)materials in a simple and convenient way to form a heterogeneous structure.Various performance enhancements have been realized through the formation of typeⅡenergy bands in heterostructures,opening up new research directions for the future development of photodetector devices.This work successfully fabricated a high-sensitivity photodetector based on WS_(2)QDs/GaAs NWs heterostructure.Under 660 nm laser excitation,the photodetector exhibits a responsivity of 368.07 A/W,a detectivity of 2.7×10^(12)Jones,an external quantum efficiency of 6.47×10^(2)%,a low-noise equivalent power of 2.27×10^(-17)W·Hz^(-1/2),a response time of 0.3 s,and a recovery time of 2.12 s.This study provides a new solution for the preparation of high-performance GaAs detectors and promotes the development of optoelectronic devices for GaAs NWs.展开更多
In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visibl...In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visible light detection perfor-mance of the heterojunction device.At 380 nm,the responsivity and detectivity of TiO_(2)@GaO_(x)N_(y)-Ag were 0.94 A/W and 4.79×109 Jones,respectively,and they increased to 2.86 A/W and 7.96×1010 Jones at 580 nm.The rise and fall times of the response were 0.19/0.23 and 0.50/0.57 s,respectively.Uniquely,at 580 nm,the responsivity of fabricated devices is one to four orders of magnitude higher than that of the photodetectors based on TiO_(2),Ga_(2)O_(3),and other heterojunctions.The excellent optoelectronic characteristics of the TiO_(2)@GaO_(x)N_(y)-Ag heterojunction device could be mainly attributed to the synergistic effect of the type-Ⅱband structure of the metal-semiconductor-metal heterojunction and the plasmon resonance effect of Ag,which not only effectively promotes the separation of photogenerated carriers but also reduces the recombination rate.It is fur-ther illuminated by finite difference time domain method(FDTD)simulation and photoelectric measurements.The TiO_(2)@GaO_(x)N_(y)-Ag arrays with high-efficiency detection are suitable candidates for applications in energy-saving communica-tion,imaging,and sensing networks.展开更多
Vertically stacked heterostructures have received extensive attention because of their tunable electronic structures and outstanding optical properties.In this work,we study the structural,electronic,and optical prope...Vertically stacked heterostructures have received extensive attention because of their tunable electronic structures and outstanding optical properties.In this work,we study the structural,electronic,and optical properties of vertically stacked GaS-SnS_(2)heterostructure under the frame of density functional theory.We find that the stacked GaS-SnS_(2)heterostructure is a semiconductor with a suitable indirect band gap of 1.82 eV,exhibiting a type-Ⅱband alignment for easily separating the photo-generated carriers.The electronic properties of GaS-SnS_(2)hetero structure can be effectively tuned by an external strain and electric field.The optical absorption of GaS-SnS_(2)heterostructure is more enhanced than those of the GaS monolayer and SnS_(2)monolayer in the visible light region.Our results suggest that the GaS-SnS_(2)hetero structure is a promising candidate for the photocatalyst and photoelectronic devices in the visible light region.展开更多
Owing to its outstanding electronic properties, black phosphorus （BP） is considered as a promis- ing material for next-generation optoelectronic devices. In this work, devices based on BP/MXene （Zrn＋1CnT2, T = O, ...Owing to its outstanding electronic properties, black phosphorus （BP） is considered as a promis- ing material for next-generation optoelectronic devices. In this work, devices based on BP/MXene （Zrn＋1CnT2, T = O, F, OH, n = 1, 2） van der Waals （vdW） heterostructures are designed via first-principles calculations. Zrn＋1CnW2 compositions with appropriate work functions lead to the for- mation of Ohmic contact with BP in the vertical direction. Low Schottky barriers are found along the lateral direction in BP/Zr2CF2, BP/Zr2CO2H2, BP/Zr3C2F2, and BP/Zr3C2O2H2 bilayers, and BP/Zr3C202 even exhibits Ohmic contact behavior. BP/Zr2CO2 is a semiconducting heterostructure with type-II band alignment, which facilitates the separation of electron-hole pairs. The band struc- ture of BP/Zr2CO2 can be effectively tuned via a perpendicular electric field, and BP is predicted to undergo a transition from donor to acceptor at a 0.4 V/A electric field. The versatile electronic prop- erties of the BP/MXene heterostructures examined in this work highlight their promising potential for applications in electronics.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2019YFB1503601 and 2017YFB0405302)the National Natural Science Foundation of China(Grant Nos.61574139 and U1738114)the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(Grant No.XDA15051200)。
文摘Aiming to achieve InAs quantum dots(QDs) with a long carrier lifetime,the effects of Sb component in cap layers on the band alignment of the InAs/GaAsSb QDs have been studied.InAs QDs with high density and uniformity have been grown by molecular beam epitaxy.With increasing Sb composition,the InAs/GaAsSb QDs exhibit a significant redshift and broadening photoluminescence(PL).With a high Sb component of 22%,the longest wavelength emission of the InAs/GaAs_(0.78)Sb_(0.22) QDs occurs at 1.5 μm at room temperature.The power-dependence PL measurements indicate that with a low Sb component of 14%,the InAs/GaAs_(0.86)Sb_(0.14) QDs have a type-Ⅰ and a type-Ⅱ carrier recombination processes,respectively.With a high Sb component of 22%,the InAs/GaAs_(0.78)Sb_(0.22) QDs have a pure type-Ⅱ band alignment,with three type-Ⅱ carrier recombination processes.Extracted from time-resolved PL decay traces,the carrier lifetime of the InAs/GaAs_(0.78)Sb_(0.22) QDs reaches 16.86 ns,which is much longer than that of the InAs/GaAs_(0.86)Sb_(0.14) QDs(2.07 ns).These results obtained here are meaningful to realize high conversion efficiency intermediate-band QD solar cells and other opto-electronic device.
文摘The performance of the photodetector is significantly impacted by the inherent surface faults in GaAs nanowires(NWs).We combined three-dimensional(3D)gallium arsenide nanowires with zero-dimensional(0D)WS_(2) quantum dot(QDs)materials in a simple and convenient way to form a heterogeneous structure.Various performance enhancements have been realized through the formation of typeⅡenergy bands in heterostructures,opening up new research directions for the future development of photodetector devices.This work successfully fabricated a high-sensitivity photodetector based on WS_(2)QDs/GaAs NWs heterostructure.Under 660 nm laser excitation,the photodetector exhibits a responsivity of 368.07 A/W,a detectivity of 2.7×10^(12)Jones,an external quantum efficiency of 6.47×10^(2)%,a low-noise equivalent power of 2.27×10^(-17)W·Hz^(-1/2),a response time of 0.3 s,and a recovery time of 2.12 s.This study provides a new solution for the preparation of high-performance GaAs detectors and promotes the development of optoelectronic devices for GaAs NWs.
基金supported by National Natural Science Foundation of China(Nos.62027818,61874034,and 51861135105)Natural Science Foundation of Shanghai(No.18ZR1405000)Shanghai Science and Technology Innovation Program(No.19520711500).
文摘In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visible light detection perfor-mance of the heterojunction device.At 380 nm,the responsivity and detectivity of TiO_(2)@GaO_(x)N_(y)-Ag were 0.94 A/W and 4.79×109 Jones,respectively,and they increased to 2.86 A/W and 7.96×1010 Jones at 580 nm.The rise and fall times of the response were 0.19/0.23 and 0.50/0.57 s,respectively.Uniquely,at 580 nm,the responsivity of fabricated devices is one to four orders of magnitude higher than that of the photodetectors based on TiO_(2),Ga_(2)O_(3),and other heterojunctions.The excellent optoelectronic characteristics of the TiO_(2)@GaO_(x)N_(y)-Ag heterojunction device could be mainly attributed to the synergistic effect of the type-Ⅱband structure of the metal-semiconductor-metal heterojunction and the plasmon resonance effect of Ag,which not only effectively promotes the separation of photogenerated carriers but also reduces the recombination rate.It is fur-ther illuminated by finite difference time domain method(FDTD)simulation and photoelectric measurements.The TiO_(2)@GaO_(x)N_(y)-Ag arrays with high-efficiency detection are suitable candidates for applications in energy-saving communica-tion,imaging,and sensing networks.
基金Project supported by the National Natural Science Foundation of China(Grant No.1186040026)the Incubation Project for High-Level Scientific Research Achievements of Hubei Minzu University,China(Grant No.4205009)the Fund of the Educational Commission of Hubei Province,China(Grant No.T201914)。
文摘Vertically stacked heterostructures have received extensive attention because of their tunable electronic structures and outstanding optical properties.In this work,we study the structural,electronic,and optical properties of vertically stacked GaS-SnS_(2)heterostructure under the frame of density functional theory.We find that the stacked GaS-SnS_(2)heterostructure is a semiconductor with a suitable indirect band gap of 1.82 eV,exhibiting a type-Ⅱband alignment for easily separating the photo-generated carriers.The electronic properties of GaS-SnS_(2)hetero structure can be effectively tuned by an external strain and electric field.The optical absorption of GaS-SnS_(2)heterostructure is more enhanced than those of the GaS monolayer and SnS_(2)monolayer in the visible light region.Our results suggest that the GaS-SnS_(2)hetero structure is a promising candidate for the photocatalyst and photoelectronic devices in the visible light region.
文摘Owing to its outstanding electronic properties, black phosphorus （BP） is considered as a promis- ing material for next-generation optoelectronic devices. In this work, devices based on BP/MXene （Zrn＋1CnT2, T = O, F, OH, n = 1, 2） van der Waals （vdW） heterostructures are designed via first-principles calculations. Zrn＋1CnW2 compositions with appropriate work functions lead to the for- mation of Ohmic contact with BP in the vertical direction. Low Schottky barriers are found along the lateral direction in BP/Zr2CF2, BP/Zr2CO2H2, BP/Zr3C2F2, and BP/Zr3C2O2H2 bilayers, and BP/Zr3C202 even exhibits Ohmic contact behavior. BP/Zr2CO2 is a semiconducting heterostructure with type-II band alignment, which facilitates the separation of electron-hole pairs. The band struc- ture of BP/Zr2CO2 can be effectively tuned via a perpendicular electric field, and BP is predicted to undergo a transition from donor to acceptor at a 0.4 V/A electric field. The versatile electronic prop- erties of the BP/MXene heterostructures examined in this work highlight their promising potential for applications in electronics.
