The thickness dependence of linearly polarized light-induced momentum anisotropy and the inverse spin Hall effect(PISHE)in topological insulator(TI)Bi_(2)Te_(3)films has been investigated.A significant enhancement of ...The thickness dependence of linearly polarized light-induced momentum anisotropy and the inverse spin Hall effect(PISHE)in topological insulator(TI)Bi_(2)Te_(3)films has been investigated.A significant enhancement of the PISHE signal is observed in the 12-quintuple-layer(QL)Bi_(2)Te_(3)film compared with that of the 3-and 5-QL samples,whereas a minimal value of photoinduced momentum anisotropy is found in the 12-QL sample.The photoinduced momentum anisotropy and the PISHE in Bi_(2)Te_(3)films are more than three and two orders of magnitude larger than those in Bi2Se3 films grown on SrTiO_(3)substrates,respectively.The 3-QL sample exhibits a sinusoidal dependence of the PISHE current on the light spot position,while the 5-QL and 12-QL samples show aW-shaped dependence,which arises from the different angles between the coordinate axis x and the in-plane crystallographic axis of the Bi_(2)Te_(3)films.Our findings demonstrate the critical role of film thickness in modulating both the photoinduced momentum anisotropy and the PISHE current,thereby suggesting a thickness-engineering strategy for designing novel optoelectronic devices based on TIs.展开更多
The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperat...The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperature. A large IPOA related to defect or impurity states is observed. The IPOA of samples grown on MoS_(2)/Mo is approximately one order of magnitude larger than that of samples grown on Ti/Mo substrates. Numerical calculations based on the envelope function approximation have been performed to analyze the origin of the IPOA. It is found that the IPOA primarily results from the segregation of indium atoms in the In Ga N/Ga N Qdisks. This work highlights the significant influence of substrate materials on the IPOA of semiconductor heterostructures.展开更多
As an alternative device for neuromorphic computing to conquer von Neumann bottleneck,the memristor serving as an artificial synapse has attracted much attention.The TaO^(x) memristors embedded with silver nanoparticl...As an alternative device for neuromorphic computing to conquer von Neumann bottleneck,the memristor serving as an artificial synapse has attracted much attention.The TaO^(x) memristors embedded with silver nanoparticles(Ag NPs)have been fabricated to implement synaptic plasticity and to investigate the effects of Ag NPs.The TaO^(x) memristors with and without Ag NPs are capable of simulating synaptic plasticity(PTP,STDP,and STP to LTP),learning,and memory behaviors.The conduction of the high resistance state(HRS) is driven by Schottky-emission mechanism.The embedment of Ag NPs causes the low resistance state(LRS) conduction governed by a Poole-Frenkel emission mechanism instead of a space-charge-limited conduction(SCLC) in a pure TaO^(x) system,which is ascribed to the Ag NPs enhancing electric field to produce additional traps and to reduce Coulomb potential energy of bound electrons to assist electron transport.Consequently,the enhanced electric fields induced by Ag NPs increase the learning strength and learning speed of the synapses.Additionally,they also improve synaptic sensitivity to stimuli.The linearity of conductance modulation and the reproducibility of conductance are improved as well.展开更多
Helicity-dependent photocurrent(HDPC)of the surface states in a high-quality topological insulator(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplate grown by chemical vapor deposition(CVD)is investigated.By investigating the angle...Helicity-dependent photocurrent(HDPC)of the surface states in a high-quality topological insulator(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplate grown by chemical vapor deposition(CVD)is investigated.By investigating the angle-dependent HDPC,it is found that the HDPC is mainly contributed by the circular photogalvanic effect(CPGE)current when the incident plane is perpendicular to the connection of the two contacts,whereas the circular photon drag effect(CPDE)dominates the HDPC when the incident plane is parallel to the connection of the two contacts.In addition,the CPGE of the(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplate is regulated by temperature,light power,excitation wavelength,the source–drain and ionic liquid top-gate voltages,and the regulation mechanisms are discussed.It is demonstrated that(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplates may provide a good platform for novel opto-spintronics devices.展开更多
The helicity-dependent photoconductance of the edge states in three-dimensional topological insulator Bi_(2)Te_(3)films is investigated.It is revealed that the helicity-dependent photoconductivity current on the left ...The helicity-dependent photoconductance of the edge states in three-dimensional topological insulator Bi_(2)Te_(3)films is investigated.It is revealed that the helicity-dependent photoconductivity current on the left edge of the Bi_(2)Te_(3)film shows an opposite sign with that on the right edge.In addition,the helicity-dependent photoconductivity current increases linearly with the applied longitudinal electric field,and it reverses the sign with the reversal of the electric field.As the thickness of the Bi_(2)Te_(3)film increases,the helicity-dependent photoconductivity current also increases.Theoretical analysis suggests that the helicity-dependent photo-conductivity current may come from the intrinsic spin orbit coupling(SOC)or the SOC introduced by the chiral impurities or defects.展开更多
Optical helicity provides us with an effective means to control the helicity-dependent photocurrent in the spinmomentum-locked surface states of topological insulators(TIs).Also,the TIs show potential in polarization ...Optical helicity provides us with an effective means to control the helicity-dependent photocurrent in the spinmomentum-locked surface states of topological insulators(TIs).Also,the TIs show potential in polarization detection as an intrinsic solid-state optical chirality detector for easier integration and fabrication.However,the complex photoresponses with the circular photogalvanic effect,the linear photogalvanic effect,and the photon drag effect in the TIs prevent them from direct chirality detection of the elliptically polarized light.Here,by fitting with the theoretical models to the measured photocurrents,the microscopic origin of different components of the helicity-dependent photocurrent has been demonstrated.We show a comprehensive study of the helicitydependent photocurrent in(Bi_(1-x)Sb_(x))_(2)Te_(3)thin films of different thicknesses as a function of the light incident angle and the gate-tuned chemical potential.The observation of the light incident angle dependence of the helicitydependent photocurrent provides us with a polarization detection strategy using a TI thin film without the use of any additional optical elements,and the detection accuracy can be enhanced by gate tuning.Additionally,the Stokes parameters can be extracted by arithmetic operation of photocurrents measured with different incident angles and gating voltages for complete characterization of the polarization states of a light beam.Using this means,we realize the polarization detection and the Stokes parameters analysis with a single device.Our work provides an alternative solution to develop miniaturized intrinsic polarization-sensitive photodetectors.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62074036,61674038,and 11574302)the Foreign Cooperation Project of Fujian Province,China(Grant No.2023I0005)+2 种基金the Open Research Fund Program of the State Key Laboratory of Low Dimensional Quantum Physics(Grant No.KF202108)the National Key Research and Development Program of China(Grant No.2016YFB0402303)the Foundation of the Fujian Provincial Department of Industry and Information Technology of China(Grant No.82318075).
文摘The thickness dependence of linearly polarized light-induced momentum anisotropy and the inverse spin Hall effect(PISHE)in topological insulator(TI)Bi_(2)Te_(3)films has been investigated.A significant enhancement of the PISHE signal is observed in the 12-quintuple-layer(QL)Bi_(2)Te_(3)film compared with that of the 3-and 5-QL samples,whereas a minimal value of photoinduced momentum anisotropy is found in the 12-QL sample.The photoinduced momentum anisotropy and the PISHE in Bi_(2)Te_(3)films are more than three and two orders of magnitude larger than those in Bi2Se3 films grown on SrTiO_(3)substrates,respectively.The 3-QL sample exhibits a sinusoidal dependence of the PISHE current on the light spot position,while the 5-QL and 12-QL samples show aW-shaped dependence,which arises from the different angles between the coordinate axis x and the in-plane crystallographic axis of the Bi_(2)Te_(3)films.Our findings demonstrate the critical role of film thickness in modulating both the photoinduced momentum anisotropy and the PISHE current,thereby suggesting a thickness-engineering strategy for designing novel optoelectronic devices based on TIs.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62074036, 61674038, and 11574302)Foreign Cooperation Project of Fujian Province (Grant No. 2023I0005)+2 种基金Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics (Grant No. KF202108)the National Key Research and Development Program (Grant No. 2016YFB0402303)the Foundation of Fujian Provincial Department of Industry and Information Technology of China (Grant No. 82318075)。
文摘The in-plane optical anisotropy(IPOA) of c-plane In Ga N/Ga N quantum disks(Qdisks) in nanowires grown on MoS_(2)/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy(RDS) at room temperature. A large IPOA related to defect or impurity states is observed. The IPOA of samples grown on MoS_(2)/Mo is approximately one order of magnitude larger than that of samples grown on Ti/Mo substrates. Numerical calculations based on the envelope function approximation have been performed to analyze the origin of the IPOA. It is found that the IPOA primarily results from the segregation of indium atoms in the In Ga N/Ga N Qdisks. This work highlights the significant influence of substrate materials on the IPOA of semiconductor heterostructures.
基金Project supported by the National Natural Science Foundation of China(Grant No.61674038)the Natural Science Foundation of Fujian Province,China(Grant No.2019J01218)+1 种基金the Fund from the Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China(Grant No.2021ZR145)the Science Fund from the Fujian Provincial Department of Industry and Information Technology of China(Grant No.82318075)。
文摘As an alternative device for neuromorphic computing to conquer von Neumann bottleneck,the memristor serving as an artificial synapse has attracted much attention.The TaO^(x) memristors embedded with silver nanoparticles(Ag NPs)have been fabricated to implement synaptic plasticity and to investigate the effects of Ag NPs.The TaO^(x) memristors with and without Ag NPs are capable of simulating synaptic plasticity(PTP,STDP,and STP to LTP),learning,and memory behaviors.The conduction of the high resistance state(HRS) is driven by Schottky-emission mechanism.The embedment of Ag NPs causes the low resistance state(LRS) conduction governed by a Poole-Frenkel emission mechanism instead of a space-charge-limited conduction(SCLC) in a pure TaO^(x) system,which is ascribed to the Ag NPs enhancing electric field to produce additional traps and to reduce Coulomb potential energy of bound electrons to assist electron transport.Consequently,the enhanced electric fields induced by Ag NPs increase the learning strength and learning speed of the synapses.Additionally,they also improve synaptic sensitivity to stimuli.The linearity of conductance modulation and the reproducibility of conductance are improved as well.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62074036,61674038,and 11574302)the Foreign Cooperation Project of Fujian Province,China(Grant No.2023I0005)+2 种基金the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics(Grant No.KF202108)the National Key Research and Development Program of China(Grant No.2016YFB0402303)the Foundation of Fujian Provincial Department of Industry and Information Technology of China(Grant No.82318075)。
文摘Helicity-dependent photocurrent(HDPC)of the surface states in a high-quality topological insulator(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplate grown by chemical vapor deposition(CVD)is investigated.By investigating the angle-dependent HDPC,it is found that the HDPC is mainly contributed by the circular photogalvanic effect(CPGE)current when the incident plane is perpendicular to the connection of the two contacts,whereas the circular photon drag effect(CPDE)dominates the HDPC when the incident plane is parallel to the connection of the two contacts.In addition,the CPGE of the(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplate is regulated by temperature,light power,excitation wavelength,the source–drain and ionic liquid top-gate voltages,and the regulation mechanisms are discussed.It is demonstrated that(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplates may provide a good platform for novel opto-spintronics devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62074036 and 61674038)the National Key Research and Development Program of China(Grant No.2016YFB0402303)。
文摘The helicity-dependent photoconductance of the edge states in three-dimensional topological insulator Bi_(2)Te_(3)films is investigated.It is revealed that the helicity-dependent photoconductivity current on the left edge of the Bi_(2)Te_(3)film shows an opposite sign with that on the right edge.In addition,the helicity-dependent photoconductivity current increases linearly with the applied longitudinal electric field,and it reverses the sign with the reversal of the electric field.As the thickness of the Bi_(2)Te_(3)film increases,the helicity-dependent photoconductivity current also increases.Theoretical analysis suggests that the helicity-dependent photo-conductivity current may come from the intrinsic spin orbit coupling(SOC)or the SOC introduced by the chiral impurities or defects.
基金National Natural Science Foundation of China(62074036,61674038,11574302)Foreign Cooperation Project of Fujian Province(2023I0005)+2 种基金Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics(KF202108)National Key Research and Development Program of China(2016YFB0402303)Foundation of Fujian Provincial Department of Industry and Information Technology(82318075)。
文摘Optical helicity provides us with an effective means to control the helicity-dependent photocurrent in the spinmomentum-locked surface states of topological insulators(TIs).Also,the TIs show potential in polarization detection as an intrinsic solid-state optical chirality detector for easier integration and fabrication.However,the complex photoresponses with the circular photogalvanic effect,the linear photogalvanic effect,and the photon drag effect in the TIs prevent them from direct chirality detection of the elliptically polarized light.Here,by fitting with the theoretical models to the measured photocurrents,the microscopic origin of different components of the helicity-dependent photocurrent has been demonstrated.We show a comprehensive study of the helicitydependent photocurrent in(Bi_(1-x)Sb_(x))_(2)Te_(3)thin films of different thicknesses as a function of the light incident angle and the gate-tuned chemical potential.The observation of the light incident angle dependence of the helicitydependent photocurrent provides us with a polarization detection strategy using a TI thin film without the use of any additional optical elements,and the detection accuracy can be enhanced by gate tuning.Additionally,the Stokes parameters can be extracted by arithmetic operation of photocurrents measured with different incident angles and gating voltages for complete characterization of the polarization states of a light beam.Using this means,we realize the polarization detection and the Stokes parameters analysis with a single device.Our work provides an alternative solution to develop miniaturized intrinsic polarization-sensitive photodetectors.
