InAs/GaAs quantum dot(QD)lasers were grown on silicon substrates using a thin Ge buffer and three-step growth method in the molecular beam epitaxy(MBE)system.In addition,strained superlattices were used to prevent thr...InAs/GaAs quantum dot(QD)lasers were grown on silicon substrates using a thin Ge buffer and three-step growth method in the molecular beam epitaxy(MBE)system.In addition,strained superlattices were used to prevent threading disloca-tions from propagating to the active region of the laser.The as-grown material quality was characterized by the transmission electron microscope,scanning electron microscope,X-ray diffraction,atomic force microscope,and photoluminescence spectro-scopy.The results show that a high-quality GaAs buffer with few dislocations was obtained by the growth scheme we de-veloped.A broad-area edge-emitting laser was also fabricated.The O-band laser exhibited a threshold current density of 540 A/cm^(2) at room temperature under continuous wave conditions.This work demonstrates the potential of large-scale and low-cost manufacturing of the O-band InAs/GaAs quantum dot lasers on silicon substrates.展开更多
In organic solar cells,the singlet and triplet excitons dissociate into free charge carriers with different mechanisms due to their opposite spin state.Therefore,the ratio of the singlet and triplet excitons directly ...In organic solar cells,the singlet and triplet excitons dissociate into free charge carriers with different mechanisms due to their opposite spin state.Therefore,the ratio of the singlet and triplet excitons directly affects the photocurrent.Many methods were used to optimize the performance of the low-efficiency solar cell by improving the ratio of triplet excitons,which shows a long diffusion length.Here we observed that in high-efficiency systems,the proportion of singlet excitons under linearly polarized light excitation is higher than that of circularly polarized light.Since the singlet charge transfer state has lower binding energy than the triplet state,it makes a significant contribution to the charge carrier generation and enhancement of the photocurrent.Further,the positive magnetic field effect reflects that singlet excitons dissociation plays a major role in the photocurrent,which is opposite to the case of low-efficiency devices where triplet excitons dominate the photocurrent.展开更多
Optical frequency combs(OFCs)have great potential in communications,especially in dense wavelength-division multiplexing.However,the size of traditional OFCs based on conventional optical microcavities or dispersion f...Optical frequency combs(OFCs)have great potential in communications,especially in dense wavelength-division multiplexing.However,the size of traditional OFCs based on conventional optical microcavities or dispersion fibers is at least tens of micrometers,far larger than that of nanoscale electronic chips.Therefore,reducing the size of OFCs to match electronic chips is of necessity.Here,for the first time to our knowledge,we introduce surface plasmon polaritons(SPPs)to the construction of OFCs to realize a miniature device.The thickness of our device is reduced below 1μm.Though the presence of SPPs may induce ohmic and scattering loss,the threshold of the device is obtained as 9μW,comparable to the conventional device.Interestingly,the response time is 13.2 ps,much faster than the optical counterparts.This work provides a feasible strategy for the miniaturization of OFCs.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2018YFB2200104)the“Strategic Priority Research Program”of the Chinese Academy of Sciences(Grant No.XDB43010102)the Frontier Science Key Research Program of CAS(Grant No.QYZDB-SSW-SLH006)。
文摘InAs/GaAs quantum dot(QD)lasers were grown on silicon substrates using a thin Ge buffer and three-step growth method in the molecular beam epitaxy(MBE)system.In addition,strained superlattices were used to prevent threading disloca-tions from propagating to the active region of the laser.The as-grown material quality was characterized by the transmission electron microscope,scanning electron microscope,X-ray diffraction,atomic force microscope,and photoluminescence spectro-scopy.The results show that a high-quality GaAs buffer with few dislocations was obtained by the growth scheme we de-veloped.A broad-area edge-emitting laser was also fabricated.The O-band laser exhibited a threshold current density of 540 A/cm^(2) at room temperature under continuous wave conditions.This work demonstrates the potential of large-scale and low-cost manufacturing of the O-band InAs/GaAs quantum dot lasers on silicon substrates.
基金the National Key Research and Development Program of China(No.2018YFE0204000)the National Natural Science Foundation of China(Nos.U20A20206,51972300,62274155,and 21975245)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB43000000)the Key Research Program of Frontier Science,Chinese Academy of Sciences(No.QYZDBSSWSLH006)K.L.appreciates the support from the Youth Innovation Promotion Association,the Chinese Academy of Sciences(No.2020114)the Beijing Nova Program(No.2020117).
文摘In organic solar cells,the singlet and triplet excitons dissociate into free charge carriers with different mechanisms due to their opposite spin state.Therefore,the ratio of the singlet and triplet excitons directly affects the photocurrent.Many methods were used to optimize the performance of the low-efficiency solar cell by improving the ratio of triplet excitons,which shows a long diffusion length.Here we observed that in high-efficiency systems,the proportion of singlet excitons under linearly polarized light excitation is higher than that of circularly polarized light.Since the singlet charge transfer state has lower binding energy than the triplet state,it makes a significant contribution to the charge carrier generation and enhancement of the photocurrent.Further,the positive magnetic field effect reflects that singlet excitons dissociation plays a major role in the photocurrent,which is opposite to the case of low-efficiency devices where triplet excitons dominate the photocurrent.
基金National Key Research and Development Program of China(2018YFE0204000)Strategic Priority Research Program of the Chinese Academy of Sciences(XDB43000000)+2 种基金National Natural Science Foundation of China(21975245,51972300,62274155,U20A20206)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2020114)Beijing Nova Program(2020117)。
文摘Optical frequency combs(OFCs)have great potential in communications,especially in dense wavelength-division multiplexing.However,the size of traditional OFCs based on conventional optical microcavities or dispersion fibers is at least tens of micrometers,far larger than that of nanoscale electronic chips.Therefore,reducing the size of OFCs to match electronic chips is of necessity.Here,for the first time to our knowledge,we introduce surface plasmon polaritons(SPPs)to the construction of OFCs to realize a miniature device.The thickness of our device is reduced below 1μm.Though the presence of SPPs may induce ohmic and scattering loss,the threshold of the device is obtained as 9μW,comparable to the conventional device.Interestingly,the response time is 13.2 ps,much faster than the optical counterparts.This work provides a feasible strategy for the miniaturization of OFCs.
