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
The influence of InAs deposition thickness on the structural and optical properties of InAs/InA1As quantum wires （QWR） superlattices （SLS） was studied. The transmission electron microscopy （TEM） results show tha...The influence of InAs deposition thickness on the structural and optical properties of InAs/InA1As quantum wires （QWR） superlattices （SLS） was studied. The transmission electron microscopy （TEM） results show that with increasing the InAs deposited thickness, the size uniformity and spatial ordering of InAs QWR SLS was greatly improved, but threading dislocations initiated from InAs nanowires for the sample with 6 monolayers （MLs） InAs deposition. In addition, the zig-zag features along the extending direc- tion and lateral interlink of InAs nanowires were also observed. The InAs nanowires, especially for the first period, were laterally compact. These structural features may result in easy tunneling and coupling of charge carders between InAs nanowires and will hamper their device applications to some extent. Some suggestions are put forward for further improving the uniformity of the stacked InAs QWRs, and for suppressing the formation of the threading dislocations in InAs QWR SLS.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
InAs-based interband cascade lasers（ICLs） with InAs plasmon waveguides or InAs/AlSb superlattice（SL） waveguides were demonstrated at emission wavelengths below 4.1 μm. The threshold current densities of the laser...InAs-based interband cascade lasers（ICLs） with InAs plasmon waveguides or InAs/AlSb superlattice（SL） waveguides were demonstrated at emission wavelengths below 4.1 μm. The threshold current densities of the lasers with SL waveguides were 37 A/cm;at 77 K in continuous wave mode. The operation temperature of these lasers reached room temperature in pulsed mode. Compared with the thick InAs n++ plasmon cladding layer, the InAs/AlSb superlattice cladding layers have greater advantages for ICLs with wavelengths less than 4 μm even in InAs based ICLs because in the short-wavelength region they have a higher confinement factor than InAs plasmon waveguides.展开更多
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Special Funds for Major State Basic Research Project of China (No.G2000068303)Na-tional Natural Science Foundation of China (No.60390074, 60390071, 90101004)National High-Tech Research and Develop-ment Program of China (No.2002AA311070).
文摘The influence of InAs deposition thickness on the structural and optical properties of InAs/InA1As quantum wires （QWR） superlattices （SLS） was studied. The transmission electron microscopy （TEM） results show that with increasing the InAs deposited thickness, the size uniformity and spatial ordering of InAs QWR SLS was greatly improved, but threading dislocations initiated from InAs nanowires for the sample with 6 monolayers （MLs） InAs deposition. In addition, the zig-zag features along the extending direc- tion and lateral interlink of InAs nanowires were also observed. The InAs nanowires, especially for the first period, were laterally compact. These structural features may result in easy tunneling and coupling of charge carders between InAs nanowires and will hamper their device applications to some extent. Some suggestions are put forward for further improving the uniformity of the stacked InAs QWRs, and for suppressing the formation of the threading dislocations in InAs QWR SLS.
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.
基金Project supported by the National Natural Science Foundation of China(Nos.61790583,61774150,61774151)the National Basic Research Program of China(No.2014CB643903)
文摘InAs-based interband cascade lasers（ICLs） with InAs plasmon waveguides or InAs/AlSb superlattice（SL） waveguides were demonstrated at emission wavelengths below 4.1 μm. The threshold current densities of the lasers with SL waveguides were 37 A/cm;at 77 K in continuous wave mode. The operation temperature of these lasers reached room temperature in pulsed mode. Compared with the thick InAs n++ plasmon cladding layer, the InAs/AlSb superlattice cladding layers have greater advantages for ICLs with wavelengths less than 4 μm even in InAs based ICLs because in the short-wavelength region they have a higher confinement factor than InAs plasmon waveguides.
