The development of quantum materials for single-photon emission is crucial for the advancement of quantum information technology.Although significant advancements have been witnessed in recent years for single-photon ...The development of quantum materials for single-photon emission is crucial for the advancement of quantum information technology.Although significant advancements have been witnessed in recent years for single-photon sources in the near-infrared band(λ∼700–1000 nm),several challenges have yet to be addressed for ideal single-photon emission at the telecommunication band.In this study,we present a droplet-epitaxy strategy for O-band to C-band single-photon source-based semiconductor quantum dots(QDs)using metal-organic vaporphase epitaxy(MOVPE).By investigating the growth conditions of the epitaxial process,we have successfully synthesized InAs/InP QDs with narrow emission lines spanning a broad spectral range of λ∼1200–1600 nm.The morphological and optical properties of the samples were characterized using atomic force microscopy and microphotoluminescence spectroscopy.The recorded single-photon purity of a plain QD structure reaches g^((2))(0)=0.16,with a radiative recombination lifetime as short as 1.5 ns.This work provides a crucial platform for future research on integrated microcavity enhancement techniques and coupled QDs with other quantum photonics in the telecom bands,offering significant prospects for quantum network applications.展开更多
针对传统模型因缺少对电磁相互作用的表征而导致高频精度不足的问题,以具有优异高频特性的磷化铟高电子迁移率场效应晶体管(indium phosphide high electron mobility field-effect transistor,InP HEMT)为例,提出一种引入寄生耦合效应...针对传统模型因缺少对电磁相互作用的表征而导致高频精度不足的问题,以具有优异高频特性的磷化铟高电子迁移率场效应晶体管(indium phosphide high electron mobility field-effect transistor,InP HEMT)为例,提出一种引入寄生耦合效应的小信号等效电路模型与高频等效噪声电路模型.首先引入栅极–漏极之间的互感元件来模拟器件在高频下由于电磁相互作用产生的寄生耦合效应,并采用电磁仿真与直接参数提取相结合的建模方法,建立小信号等效电路模型.然后以所建小信号模型为基础,通过相关噪声矩阵与噪声参数的提取方法,建立高频等效噪声电路模型.实验结果表明,在500 MHz~50 GHz频段内,S参数最大误差小于3%,四噪声参数相较于传统模型提升约2.45%,并从小信号电流增益(|h21|)、单边功率增益(U)与最小噪声系数(Fmin)出发,评估了寄生耦合效应对高频性能的影响.展开更多
The band alignment of HfO2 film on p-type （100） InP substrate grown by magnetron sputtering was investigated.The chemical states and bonding characteristics of the system were characterized by X-ray photoelectron sp...The band alignment of HfO2 film on p-type （100） InP substrate grown by magnetron sputtering was investigated.The chemical states and bonding characteristics of the system were characterized by X-ray photoelectron spectroscopy （XPS）.The results show that there is no existence of Hf-P or Hf-In and there are interfacial In2O3 and InPO4 at the interface.Ultraviolet spectrophotometer （UVS） was employed to obtain the band gap value of HfO2.In 3d and Hf 4f core-level spectra and valence spectra were employed to obtain the valence band offset of HfO2/InP.Experimental results show that the （5.88 ± 0.05） eV band gap of HfO2 is aligned to the band gap of InP with a conduction band offset （△Ec） of （2.74 ± 0.05） eV and a valence band offset （△Ev） of （1.80 ± 0.05） eV.Compared with HfO2 on Si,HfO2 on InP exhibits a much larger conduction band offset （1.35 eV larger）,which is beneficial to suppress the tunneling leakage current.展开更多
In this work,we investigate the impact of the whole small recess offset on DC and RF characteristics of InP high electron mobility transistors(HEMTs).L_(g)=80 nm HEMTs are fabricated with a double-recessed gate proces...In this work,we investigate the impact of the whole small recess offset on DC and RF characteristics of InP high electron mobility transistors(HEMTs).L_(g)=80 nm HEMTs are fabricated with a double-recessed gate process.We focus on their DC and RF responses,including the maximum transconductance(g_(m_max)),ON-resistance(R_(ON)),current-gain cutoff frequency(f_(T)),and maximum oscillation frequency(f_(max)).The devices have almost same RON.The g_(m_max) improves as the whole small recess moves toward the source.However,a small gate to source capacitance(C_(gs))and a small drain output conductance(g_(ds))lead to the largest f_(T),although the whole small gate recess moves toward the drain leads to the smaller g_(m_max).According to the small-signal modeling,the device with the whole small recess toward drain exhibits an excellent RF characteristics,such as f_(T)=372 GHz and f_(max)=394 GHz.This result is achieved by paying attention to adjust resistive and capacitive parasitics,which play a key role in high-frequency response.展开更多
Traditional p-type colloidal quantum dot(CQD)hole transport layers(HTLs)used in CQD solar cells(CQDSCs)are commonly based on organic ligands exchange and the layer-by-layer(LbL)technique.Nonetheless,the ligand detachm...Traditional p-type colloidal quantum dot(CQD)hole transport layers(HTLs)used in CQD solar cells(CQDSCs)are commonly based on organic ligands exchange and the layer-by-layer(LbL)technique.Nonetheless,the ligand detachment and complex fabrication process introduce surface defects,compromising device stability and efficiency.In this work,we propose a solution-phase ligand exchange(SPLE)method utilizing inorganic ligands to develop stable p-type lead sulfide(PbS)CQD inks for the first time.Various amounts of tin(Ⅱ)iodide(SnI_(2))were mixed with lead halide(PbX_(2);X=I,Br)in the ligand solution.By precisely controlling the SnI_(2)concentration,we regulate the transition of PbS QDs from n-type to p-type.PbS CQDSCs were fabricated using two different HTL approaches:one with 1,2-ethanedithiol(EDT)-passivated QDs via the LbL method(control)and another with inorganic ligand-passivated QD ink(target).The target devices achieved a higher power conversion efficiency(PCE)of 10.93%,compared to 9.83%for the control devices.This improvement is attributed to reduced interfacial defects and enhanced carrier mobility.The proposed technique offers an efficient pathway for producing stable p-type PbS CQD inks using inorganic ligands,paving the way for high-performance and flexible CQD-based optoelectronic devices.展开更多
Realizing the high thermoelectric performance of p-type AgBiSe_(2)-based materials has been challenging due to their low p-type dopability.This work demonstrated that Cd doping at the Bi site converts n-type AgBiSe_(2...Realizing the high thermoelectric performance of p-type AgBiSe_(2)-based materials has been challenging due to their low p-type dopability.This work demonstrated that Cd doping at the Bi site converts n-type AgBiSe_(2) to p-type.The hole concentration is effectively increased with increasing Cd doping content,thereby enhancing the electrical conductivity.Theoretical calculations reveal that Cd doping flattens the edge of the valence band,resulting in an increase in the density-of-states effective mass and Seebeck coefficient.A record-high power factor of~6.2µW·cm^(−1)·K^(−2) was achieved at room temperature.Furthermore,the induced dislocations enhance the phonon scattering,contributing to the ultralow lattice thermal conductivity across the entire temperature range.As a result,a decent figure of merit(zT)of~0.3 at room temperature and a peak zT of~0.5 at 443 K were obtained in AgBi0.92Cd0.08Se_(2).Our work provides a feasible method for optimizing the thermoelectric performance of p-type AgBiSe_(2).展开更多
In this work,the incorporation of tantalum(Ta)into p-type metal-oxide(SnO_(x))semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors(TFTs)....In this work,the incorporation of tantalum(Ta)into p-type metal-oxide(SnO_(x))semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors(TFTs).The Ta-doped SnO_(x)(SnO_(x):Ta)film is deposited by radio-frequency(RF)magnetron sputtering with a Sn:Ta(3 at.%)target and thermally annealed at 270℃ for 30 min.Here,we observe that the SnO_(x):Ta film presents increased crystallinity,reduced defect density(3.25×10^(12)cm^(−2)·eV^(−1)),and widened bandgap(1.98 eV),in comparison with the undoped SnO_(x)film.As a result,the SnO_(x):Ta TFTs exhibit a lower off-state current(Ioff),an improved on/off current ratio(2.17×10^(4)),a remarkably decreased subthreshold swing(SS)by 41%,and enhanced device stability.Additionally,by introducing Ta dopants,the fringe effect as well as the impact of channel width-to-length ratio(W/L)on electrical performances of the p-type oxide TFTs can be effectively suppressed.These results shall contribute to further exploration and development of p-type SnO_(x)TFTs.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.12494604,12393834,12393831,62274014,6223501662335015)the National Key R&D Program of China (Grant No.2024YFA1208900)。
文摘The development of quantum materials for single-photon emission is crucial for the advancement of quantum information technology.Although significant advancements have been witnessed in recent years for single-photon sources in the near-infrared band(λ∼700–1000 nm),several challenges have yet to be addressed for ideal single-photon emission at the telecommunication band.In this study,we present a droplet-epitaxy strategy for O-band to C-band single-photon source-based semiconductor quantum dots(QDs)using metal-organic vaporphase epitaxy(MOVPE).By investigating the growth conditions of the epitaxial process,we have successfully synthesized InAs/InP QDs with narrow emission lines spanning a broad spectral range of λ∼1200–1600 nm.The morphological and optical properties of the samples were characterized using atomic force microscopy and microphotoluminescence spectroscopy.The recorded single-photon purity of a plain QD structure reaches g^((2))(0)=0.16,with a radiative recombination lifetime as short as 1.5 ns.This work provides a crucial platform for future research on integrated microcavity enhancement techniques and coupled QDs with other quantum photonics in the telecom bands,offering significant prospects for quantum network applications.
文摘针对传统模型因缺少对电磁相互作用的表征而导致高频精度不足的问题,以具有优异高频特性的磷化铟高电子迁移率场效应晶体管(indium phosphide high electron mobility field-effect transistor,InP HEMT)为例,提出一种引入寄生耦合效应的小信号等效电路模型与高频等效噪声电路模型.首先引入栅极–漏极之间的互感元件来模拟器件在高频下由于电磁相互作用产生的寄生耦合效应,并采用电磁仿真与直接参数提取相结合的建模方法,建立小信号等效电路模型.然后以所建小信号模型为基础,通过相关噪声矩阵与噪声参数的提取方法,建立高频等效噪声电路模型.实验结果表明,在500 MHz~50 GHz频段内,S参数最大误差小于3%,四噪声参数相较于传统模型提升约2.45%,并从小信号电流增益(|h21|)、单边功率增益(U)与最小噪声系数(Fmin)出发,评估了寄生耦合效应对高频性能的影响.
基金financially supported by the National Natural Science Foundation of China(Nos.50932001,51102020,and 51202013)
文摘The band alignment of HfO2 film on p-type （100） InP substrate grown by magnetron sputtering was investigated.The chemical states and bonding characteristics of the system were characterized by X-ray photoelectron spectroscopy （XPS）.The results show that there is no existence of Hf-P or Hf-In and there are interfacial In2O3 and InPO4 at the interface.Ultraviolet spectrophotometer （UVS） was employed to obtain the band gap value of HfO2.In 3d and Hf 4f core-level spectra and valence spectra were employed to obtain the valence band offset of HfO2/InP.Experimental results show that the （5.88 ± 0.05） eV band gap of HfO2 is aligned to the band gap of InP with a conduction band offset （△Ec） of （2.74 ± 0.05） eV and a valence band offset （△Ev） of （1.80 ± 0.05） eV.Compared with HfO2 on Si,HfO2 on InP exhibits a much larger conduction band offset （1.35 eV larger）,which is beneficial to suppress the tunneling leakage current.
基金Supported by the Terahertz Multi User RF Transceiver System Development Project(Z211100004421012).
文摘In this work,we investigate the impact of the whole small recess offset on DC and RF characteristics of InP high electron mobility transistors(HEMTs).L_(g)=80 nm HEMTs are fabricated with a double-recessed gate process.We focus on their DC and RF responses,including the maximum transconductance(g_(m_max)),ON-resistance(R_(ON)),current-gain cutoff frequency(f_(T)),and maximum oscillation frequency(f_(max)).The devices have almost same RON.The g_(m_max) improves as the whole small recess moves toward the source.However,a small gate to source capacitance(C_(gs))and a small drain output conductance(g_(ds))lead to the largest f_(T),although the whole small gate recess moves toward the drain leads to the smaller g_(m_max).According to the small-signal modeling,the device with the whole small recess toward drain exhibits an excellent RF characteristics,such as f_(T)=372 GHz and f_(max)=394 GHz.This result is achieved by paying attention to adjust resistive and capacitive parasitics,which play a key role in high-frequency response.
基金supported by MEXT KAKENHI Grant(24K01295,26286013).
文摘Traditional p-type colloidal quantum dot(CQD)hole transport layers(HTLs)used in CQD solar cells(CQDSCs)are commonly based on organic ligands exchange and the layer-by-layer(LbL)technique.Nonetheless,the ligand detachment and complex fabrication process introduce surface defects,compromising device stability and efficiency.In this work,we propose a solution-phase ligand exchange(SPLE)method utilizing inorganic ligands to develop stable p-type lead sulfide(PbS)CQD inks for the first time.Various amounts of tin(Ⅱ)iodide(SnI_(2))were mixed with lead halide(PbX_(2);X=I,Br)in the ligand solution.By precisely controlling the SnI_(2)concentration,we regulate the transition of PbS QDs from n-type to p-type.PbS CQDSCs were fabricated using two different HTL approaches:one with 1,2-ethanedithiol(EDT)-passivated QDs via the LbL method(control)and another with inorganic ligand-passivated QD ink(target).The target devices achieved a higher power conversion efficiency(PCE)of 10.93%,compared to 9.83%for the control devices.This improvement is attributed to reduced interfacial defects and enhanced carrier mobility.The proposed technique offers an efficient pathway for producing stable p-type PbS CQD inks using inorganic ligands,paving the way for high-performance and flexible CQD-based optoelectronic devices.
基金supported by the Fundamental Research Funds for the Central Universities(No.G2022WD01007)the Natural Science Foundation of Shaanxi Province(No.2023-JC-QN-0380)+2 种基金Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515111200 and 2021A1515111155)Nantong Natural Science Foundation(No.JC2023080)the Basic Research Programs of Taicang(Nos.TC2022JC08 and TC2023JC03).
文摘Realizing the high thermoelectric performance of p-type AgBiSe_(2)-based materials has been challenging due to their low p-type dopability.This work demonstrated that Cd doping at the Bi site converts n-type AgBiSe_(2) to p-type.The hole concentration is effectively increased with increasing Cd doping content,thereby enhancing the electrical conductivity.Theoretical calculations reveal that Cd doping flattens the edge of the valence band,resulting in an increase in the density-of-states effective mass and Seebeck coefficient.A record-high power factor of~6.2µW·cm^(−1)·K^(−2) was achieved at room temperature.Furthermore,the induced dislocations enhance the phonon scattering,contributing to the ultralow lattice thermal conductivity across the entire temperature range.As a result,a decent figure of merit(zT)of~0.3 at room temperature and a peak zT of~0.5 at 443 K were obtained in AgBi0.92Cd0.08Se_(2).Our work provides a feasible method for optimizing the thermoelectric performance of p-type AgBiSe_(2).
基金supported in part by National Key R&D Program of China(Grant No.2022YFE0141500)National Natural Science Foundation of China(Grant Nos.62004065 and 62274059).
文摘In this work,the incorporation of tantalum(Ta)into p-type metal-oxide(SnO_(x))semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors(TFTs).The Ta-doped SnO_(x)(SnO_(x):Ta)film is deposited by radio-frequency(RF)magnetron sputtering with a Sn:Ta(3 at.%)target and thermally annealed at 270℃ for 30 min.Here,we observe that the SnO_(x):Ta film presents increased crystallinity,reduced defect density(3.25×10^(12)cm^(−2)·eV^(−1)),and widened bandgap(1.98 eV),in comparison with the undoped SnO_(x)film.As a result,the SnO_(x):Ta TFTs exhibit a lower off-state current(Ioff),an improved on/off current ratio(2.17×10^(4)),a remarkably decreased subthreshold swing(SS)by 41%,and enhanced device stability.Additionally,by introducing Ta dopants,the fringe effect as well as the impact of channel width-to-length ratio(W/L)on electrical performances of the p-type oxide TFTs can be effectively suppressed.These results shall contribute to further exploration and development of p-type SnO_(x)TFTs.
