The In segregation and its suppression in InGaAs/AlGaAs quantum well are investigated by using high-resolution x-ray diffraction(XRD)and photoluminescence(PL),combined with the state-of-the-art aberration corrected sc...The In segregation and its suppression in InGaAs/AlGaAs quantum well are investigated by using high-resolution x-ray diffraction(XRD)and photoluminescence(PL),combined with the state-of-the-art aberration corrected scanning transmission electron microscopy(Cs-STEM)techniques.To facility our study,we grow two multiple quantum wells(MQWs)samples,which are almost identical except that in sample B a thin GaAs layer is inserted in each of the InGaAs well and AlGaAs barrier layer comparing to pristine InGaAs/AlGaAs MQWs(sample A).Our study indeed shows the direct evidences that In segregation occurs in the InGaAs/AlGaAs interface,and the effect of the Ga As insertion layer on suppressing the segregation of In atoms is also demonstrated on the atomic-scale.Therefore,the atomic-scale insights are provided to understand the segregation behavior of In atoms and to unravel the underlying mechanism of the effect of GaAs insertion layer on the improvement of crystallinity,interface roughness,and further an enhanced optical performance of InGaAs/AlGaAs QWs.展开更多
We design and fabricate a 128 × 128 AlGaAs/GaAs quantum well infrared photodetector focal plane array （FPA）. The device is achieved by metal organic chemical vapor deposition and GaAs integrated circuit process...We design and fabricate a 128 × 128 AlGaAs/GaAs quantum well infrared photodetector focal plane array （FPA）. The device is achieved by metal organic chemical vapor deposition and GaAs integrated circuit processing technology. A test structure of the photodetector with a mesa size of 300μm × 300μm is also made in order to obtain the device parameters. The measured dark current density at 77K is 1.5 × 10^-3A/cm^2 with a bias voltage of 2V. The peak of the responsivity spectrum is at 8.4μm,with a cutoff wavelength of 9μm. The blackbody detectivity is shown to be 3.95 × 10^8 （cm · Hz^1/2）/W. The final FPA is flip-chip bonded on a CMOS read-out integrated circuit. The infrared thermal images of some targets at room temperature background are successfully demonstrated at 80K operating temperature with a ratio of dead pixels of less than 1%.展开更多
A complete quantum mechanical model for GaAs?AlGaAs quantum well infrared photodetectors(QWIPs) is presented here. The model consisted of four parts: (1) Starting with the description of the electromagnetic field of t...A complete quantum mechanical model for GaAs?AlGaAs quantum well infrared photodetectors(QWIPs) is presented here. The model consisted of four parts: (1) Starting with the description of the electromagnetic field of the infrared radiation in the QWIP, effective component of the vector potential <| A z |> along the QWIP growth direction ( z axis) due to the optical diffraction grating was calculated. (2) From the wave transmissions and the occupations of the electronic states, it was discussed that the dark current in the QWIP is determined by the drift diffusion current of carriers thermally excited from the ground sublevel in the quantum well to extended states above the barrier. (3) The photocurrent was investigated by the optical transition (absorption coefficient between the ground state to excited states due to the nonzero <| A z |> ). (4) By studying the inter diffusion of the Al atoms across the GaAs?AlGaAs heterointerfaces,the mobility of the drift diffusion carriers in the excited states was calculated, so the measurement results of the dark current and photocurrent spectra can be explained theoretically. With the complete quantum mechanical descriptions of (1 4), QWIP device design and optimization are possible.展开更多
Strained InGaAs/GaAs quantum well (QW) was grown by low-pressuremetallorganic chemical vapor deposition (MOCVD). Growth interruption and strain buffer layer wereintroduced to improve the photoluminescence (PL) perform...Strained InGaAs/GaAs quantum well (QW) was grown by low-pressuremetallorganic chemical vapor deposition (MOCVD). Growth interruption and strain buffer layer wereintroduced to improve the photoluminescence (PL) performance of the InGaAs/GaAs quantum well. GoodPL results were obtained under condition of growth an interruption of 10 s combined with a moderatestrain buffer layer. Wavelength lasers of 1064 nm using the QW were grown and processed intodevices. Broad area lasers (100 μm x 500 μm) show very low threshold current densities (43 A/cm^2)and high slop efficiency (0.34 W/A, per facet).展开更多
The partial disordering of GaAs/AlGaAs quantum well(QW)material has been obtained by rapid thermal annealing with SO2 dielectric capping film.In this case,the absorption edge of QW material was shifted apparently.A la...The partial disordering of GaAs/AlGaAs quantum well(QW)material has been obtained by rapid thermal annealing with SO2 dielectric capping film.In this case,the absorption edge of QW material was shifted apparently.A laser and a modulator were integrated on a same chip by partial disordering process on the select4d area of QW wafer which was grown by molecular beam epitaxy.展开更多
We discuss the realization of broadband wavelength detection by demonstrating the longest cutoff wavelength(λc=28.6μm)far-infrared GaAs/AIGaAs quantum well infrared photodetectors(QWIPs).The responsivity is comparab...We discuss the realization of broadband wavelength detection by demonstrating the longest cutoff wavelength(λc=28.6μm)far-infrared GaAs/AIGaAs quantum well infrared photodetectors(QWIPs).The responsivity is comparable to that of mid-infrared GaAs/AIGaAs and InGaAs/GaAs QWIPs,with a responsivity of 0.265 A/W and detectivity of 3.4x109 cm.Hz1/2/W at the peak wavelength of 26.9μm at 4.2K.Based on the temperature-dependent dark current and response results,it is expected that similar performance can be obtained at least up to 20 K.Several ways to expand the wavelength coverage are also addressed.展开更多
We present room temperature femtosecond rejection studies on the photocarrier dynamics of GaAs and GaAs/AlGaAs multiple quantum wells(MQW).A rising wing with a time constant of about.5 ps and an increased amplitude pe...We present room temperature femtosecond rejection studies on the photocarrier dynamics of GaAs and GaAs/AlGaAs multiple quantum wells(MQW).A rising wing with a time constant of about.5 ps and an increased amplitude per carrier is observed for the MQW sample at carrier densities lower than 5×10^(11) cm^(-2).This phenomenon is explained as the saturation of the excitonic transitions.展开更多
Using photoreflectance(PR)at room temperature,we have studied GaAs/AlGaAs multi-quantum wells(MQWs)grown by molecular beam epitaxy.Analysis shows that the modulation mechanism of PR of MQWs is Stark shift of the subba...Using photoreflectance(PR)at room temperature,we have studied GaAs/AlGaAs multi-quantum wells(MQWs)grown by molecular beam epitaxy.Analysis shows that the modulation mechanism of PR of MQWs is Stark shift of the subbands produced by photo-injection of carriers,which has first derivative functional lineshapes.By fitting the experimental spectra,an unusual transition coming from the interfaces in MQWs was observed.展开更多
The 808-nm vertical cavity surface emitting laser(VCSEL) with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is designed and fabricated. Compared with the VCSELs with Al_(0.05)Ga_(0.95)As/Al_(...The 808-nm vertical cavity surface emitting laser(VCSEL) with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is designed and fabricated. Compared with the VCSELs with Al_(0.05)Ga_(0.95)As/Al_(0.3)Ga_(0.7)As quantum wells, the VCSEL with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is demonstrated to possess higher power conversion efficiency(PCE) and better temperature stability. The maximum PCE of 43.8% for 10-μm VCSEL is achieved at an ambient temperature of 30°C. The size-dependent thermal characteristics are also analyzed by characterizing the spectral power and output power. It demonstrates that small oxide-aperture VCSELs are advantageous for temperature-stable performance.展开更多
The carrier-density-dependent spin relaxation dynamics for modulation-doped GaAs/Al0.3 Gao,TAs quantum wells is studied using the time-resolved magneto-Kerr rotation measurements. The electron spin relaxation time and...The carrier-density-dependent spin relaxation dynamics for modulation-doped GaAs/Al0.3 Gao,TAs quantum wells is studied using the time-resolved magneto-Kerr rotation measurements. The electron spin relaxation time and its in-plane anisotropy are studied as a function of the optically injected electron density, Moreover, the relative strength of the Rashba and the Dresselhaus spin-rbit coupling fields, and thus the observed spin relaxation time anisotropy, is further tuned by the additional excitation of a 532nm continuous wave laser, demonstrating an effective spin relaxation manipulation via an optical gating method.展开更多
Left-handedness with three zero-absorption windows is achieved in a triple-quantum-dot system. With the typ- ical parameters of a GaAs/AlGaAs heterostructure, the simultaneous negative relative electric permittivity a...Left-handedness with three zero-absorption windows is achieved in a triple-quantum-dot system. With the typ- ical parameters of a GaAs/AlGaAs heterostructure, the simultaneous negative relative electric permittivity and magnetic permeability are obtained by the adjustable incoherent pumping field and two inter-dot tunnelings. Furthermore, three zero-absorption windows in the left-handedness frequency bands are observed. The left- handedness with zero-absorption in the solid state heterostrueture may solve the challenges not only in the left-handed materials achieved by the photonic resonant scheme but also in the application of negative refractive materials with a large amount of absorption.展开更多
AlGaAs/GaAs multi-quantum well (MQW) was prepared by molecular beam epitaxy(MBE) with growth-interrupted heterointerface (GIH) method and continuous growth (CG) method, respectively. The microstructures of the MQWs we...AlGaAs/GaAs multi-quantum well (MQW) was prepared by molecular beam epitaxy(MBE) with growth-interrupted heterointerface (GIH) method and continuous growth (CG) method, respectively. The microstructures of the MQWs were characterized by double-crystal X-ray rocking curve (DCRC) and atomic force microscopy (AFM), and the photoluminescence (PL) properties of the MQWs were also studied. The MQWs grown with GIH method show that higher order satellite peaks of Pendell?sung fringes are observed in DCRC, the roughness of surface is much reduced in AFM, and the full width at half maximum (FWHM) of exciton line is much narrower in PL. The results indicate that the GIH method reduces the monolayer growth step density at the heterointerface due to the migration of surface atoms for a few minutes growth interruption, and substantially improves the quality of AlGaAs/GaAs MQWs.展开更多
对基于 Ga As/ Al Ga As系子带间吸收的一种新型量子阱红外探测器 ,采用 Poisson方程和 Schrodinger方程 ,计算了新器件结构的能带结构、电子分布特性 ,在此基础上采用热离子发射、热辅助遂穿模型对器件的暗电流特性进行了模拟 ,计算结...对基于 Ga As/ Al Ga As系子带间吸收的一种新型量子阱红外探测器 ,采用 Poisson方程和 Schrodinger方程 ,计算了新器件结构的能带结构、电子分布特性 ,在此基础上采用热离子发射、热辅助遂穿模型对器件的暗电流特性进行了模拟 ,计算结果与器件实测的暗电流特性吻合得很好 ,说明热离子发射、热辅助遂穿机制是形成器件暗电流的主要构成机制 ,增加垒高、降低阱中掺杂浓度及降低工作温度是抑制器件暗电流的主要途径 ,计算结果对进一步优化器件的设计将起到重要的理论指导作用 .展开更多
基金X.H.gratefully acknowledges the financial support from the National Natural Science Foundation of China(Grant No.21902096)the Scientific Research Foundation of Shaanxi University of Science and Technology(Grant No.126061803)+1 种基金S.M.and B.X.thank the National Natural Science Foundation of China(Grant No.21972103)the Shanxi Provincial Key Innovative Research Team in Science and Technology(Grant No.201703D111026).
文摘The In segregation and its suppression in InGaAs/AlGaAs quantum well are investigated by using high-resolution x-ray diffraction(XRD)and photoluminescence(PL),combined with the state-of-the-art aberration corrected scanning transmission electron microscopy(Cs-STEM)techniques.To facility our study,we grow two multiple quantum wells(MQWs)samples,which are almost identical except that in sample B a thin GaAs layer is inserted in each of the InGaAs well and AlGaAs barrier layer comparing to pristine InGaAs/AlGaAs MQWs(sample A).Our study indeed shows the direct evidences that In segregation occurs in the InGaAs/AlGaAs interface,and the effect of the Ga As insertion layer on suppressing the segregation of In atoms is also demonstrated on the atomic-scale.Therefore,the atomic-scale insights are provided to understand the segregation behavior of In atoms and to unravel the underlying mechanism of the effect of GaAs insertion layer on the improvement of crystallinity,interface roughness,and further an enhanced optical performance of InGaAs/AlGaAs QWs.
文摘We design and fabricate a 128 × 128 AlGaAs/GaAs quantum well infrared photodetector focal plane array （FPA）. The device is achieved by metal organic chemical vapor deposition and GaAs integrated circuit processing technology. A test structure of the photodetector with a mesa size of 300μm × 300μm is also made in order to obtain the device parameters. The measured dark current density at 77K is 1.5 × 10^-3A/cm^2 with a bias voltage of 2V. The peak of the responsivity spectrum is at 8.4μm,with a cutoff wavelength of 9μm. The blackbody detectivity is shown to be 3.95 × 10^8 （cm · Hz^1/2）/W. The final FPA is flip-chip bonded on a CMOS read-out integrated circuit. The infrared thermal images of some targets at room temperature background are successfully demonstrated at 80K operating temperature with a ratio of dead pixels of less than 1%.
文摘A complete quantum mechanical model for GaAs?AlGaAs quantum well infrared photodetectors(QWIPs) is presented here. The model consisted of four parts: (1) Starting with the description of the electromagnetic field of the infrared radiation in the QWIP, effective component of the vector potential <| A z |> along the QWIP growth direction ( z axis) due to the optical diffraction grating was calculated. (2) From the wave transmissions and the occupations of the electronic states, it was discussed that the dark current in the QWIP is determined by the drift diffusion current of carriers thermally excited from the ground sublevel in the quantum well to extended states above the barrier. (3) The photocurrent was investigated by the optical transition (absorption coefficient between the ground state to excited states due to the nonzero <| A z |> ). (4) By studying the inter diffusion of the Al atoms across the GaAs?AlGaAs heterointerfaces,the mobility of the drift diffusion carriers in the excited states was calculated, so the measurement results of the dark current and photocurrent spectra can be explained theoretically. With the complete quantum mechanical descriptions of (1 4), QWIP device design and optimization are possible.
文摘Strained InGaAs/GaAs quantum well (QW) was grown by low-pressuremetallorganic chemical vapor deposition (MOCVD). Growth interruption and strain buffer layer wereintroduced to improve the photoluminescence (PL) performance of the InGaAs/GaAs quantum well. GoodPL results were obtained under condition of growth an interruption of 10 s combined with a moderatestrain buffer layer. Wavelength lasers of 1064 nm using the QW were grown and processed intodevices. Broad area lasers (100 μm x 500 μm) show very low threshold current densities (43 A/cm^2)and high slop efficiency (0.34 W/A, per facet).
基金Supported by the National Natural Science Foundation of China,。
文摘The partial disordering of GaAs/AlGaAs quantum well(QW)material has been obtained by rapid thermal annealing with SO2 dielectric capping film.In this case,the absorption edge of QW material was shifted apparently.A laser and a modulator were integrated on a same chip by partial disordering process on the select4d area of QW wafer which was grown by molecular beam epitaxy.
基金Supported in part by the National Natural Science Foundation of China,QMX,TRAPOYT,and CKSP.
文摘We discuss the realization of broadband wavelength detection by demonstrating the longest cutoff wavelength(λc=28.6μm)far-infrared GaAs/AIGaAs quantum well infrared photodetectors(QWIPs).The responsivity is comparable to that of mid-infrared GaAs/AIGaAs and InGaAs/GaAs QWIPs,with a responsivity of 0.265 A/W and detectivity of 3.4x109 cm.Hz1/2/W at the peak wavelength of 26.9μm at 4.2K.Based on the temperature-dependent dark current and response results,it is expected that similar performance can be obtained at least up to 20 K.Several ways to expand the wavelength coverage are also addressed.
基金Supported by the Science Foundation of Zhongshan University.
文摘We present room temperature femtosecond rejection studies on the photocarrier dynamics of GaAs and GaAs/AlGaAs multiple quantum wells(MQW).A rising wing with a time constant of about.5 ps and an increased amplitude per carrier is observed for the MQW sample at carrier densities lower than 5×10^(11) cm^(-2).This phenomenon is explained as the saturation of the excitonic transitions.
文摘Using photoreflectance(PR)at room temperature,we have studied GaAs/AlGaAs multi-quantum wells(MQWs)grown by molecular beam epitaxy.Analysis shows that the modulation mechanism of PR of MQWs is Stark shift of the subbands produced by photo-injection of carriers,which has first derivative functional lineshapes.By fitting the experimental spectra,an unusual transition coming from the interfaces in MQWs was observed.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61804175)the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (Grant No. ZDBS-LY-JSC031)the China Postdoctoral Science Foundation (Grant No. BX20200358)。
文摘The 808-nm vertical cavity surface emitting laser(VCSEL) with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is designed and fabricated. Compared with the VCSELs with Al_(0.05)Ga_(0.95)As/Al_(0.3)Ga_(0.7)As quantum wells, the VCSEL with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is demonstrated to possess higher power conversion efficiency(PCE) and better temperature stability. The maximum PCE of 43.8% for 10-μm VCSEL is achieved at an ambient temperature of 30°C. The size-dependent thermal characteristics are also analyzed by characterizing the spectral power and output power. It demonstrates that small oxide-aperture VCSELs are advantageous for temperature-stable performance.
基金Supported by the National Natural Science Foundation Program of China under Grant Nos 11274302,11474276 and 61290303
文摘The carrier-density-dependent spin relaxation dynamics for modulation-doped GaAs/Al0.3 Gao,TAs quantum wells is studied using the time-resolved magneto-Kerr rotation measurements. The electron spin relaxation time and its in-plane anisotropy are studied as a function of the optically injected electron density, Moreover, the relative strength of the Rashba and the Dresselhaus spin-rbit coupling fields, and thus the observed spin relaxation time anisotropy, is further tuned by the additional excitation of a 532nm continuous wave laser, demonstrating an effective spin relaxation manipulation via an optical gating method.
基金Supported by the National Natural Science Foundation of China under Grant No 61205205the Foundation for Personnel Training Projects of Yunnan Province under Grant No KKSY201207068
文摘Left-handedness with three zero-absorption windows is achieved in a triple-quantum-dot system. With the typ- ical parameters of a GaAs/AlGaAs heterostructure, the simultaneous negative relative electric permittivity and magnetic permeability are obtained by the adjustable incoherent pumping field and two inter-dot tunnelings. Furthermore, three zero-absorption windows in the left-handedness frequency bands are observed. The left- handedness with zero-absorption in the solid state heterostrueture may solve the challenges not only in the left-handed materials achieved by the photonic resonant scheme but also in the application of negative refractive materials with a large amount of absorption.
文摘AlGaAs/GaAs multi-quantum well (MQW) was prepared by molecular beam epitaxy(MBE) with growth-interrupted heterointerface (GIH) method and continuous growth (CG) method, respectively. The microstructures of the MQWs were characterized by double-crystal X-ray rocking curve (DCRC) and atomic force microscopy (AFM), and the photoluminescence (PL) properties of the MQWs were also studied. The MQWs grown with GIH method show that higher order satellite peaks of Pendell?sung fringes are observed in DCRC, the roughness of surface is much reduced in AFM, and the full width at half maximum (FWHM) of exciton line is much narrower in PL. The results indicate that the GIH method reduces the monolayer growth step density at the heterointerface due to the migration of surface atoms for a few minutes growth interruption, and substantially improves the quality of AlGaAs/GaAs MQWs.
