在InGaAs/GaAs表面量子点(SQDs)的GaAs势垒层中引入Si掺杂层，以研究Si掺杂对InGaAs/GaAs SQDs光学特性的影响。荧光发光谱(PL)测量结果显示，InGaAs/GaAs SQDs的发光强烈依赖于Si掺杂浓度。随着掺杂浓度的增加， SQDs的PL峰值位置先红移后蓝移； PL峰值能量与激光激发强度的立方根依赖关系由线性向非线性转变；通过组态交互作用方法发现SQDs的PL峰位蓝移减弱；时间分辨荧光光谱显示了从非线性衰减到线性衰减的转变。以上结果说明Si掺杂能够填充InGaAs SQDs的表面态，并且改变表面费米能级钉扎效应和SQDs的荧光辐射特性。本研究为深入理解与InGaAs SQDs的表面敏感特性关联的物理机制和载流子动力学过程，以及扩大InGaAs/GaAs SQDs传感器的应用提供了实验依据。
InGaAs量子点 Si掺杂 表面费米能级 荧光发光谱 间接跃迁辐射 时间分辨荧光光谱 InGaAs quantum dot Si doping surface Fermi level photoluminescence indirect-transition emission time-resolved photoluminescence
Author Affiliations
Abstract
1 State Key Laboratory for Mesoscopic Physics & Department of Physics, Collaborative Innovation Center of Quantum Matter & Frontiers Science Center for Nano-optoelectronics, Beijing Academy of Quantum Information Sciences, Peking University, Beijing 100871, China
2 Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Kaiserslautern 67663, Germany
3 College of Physics Science & Technology, Hebei University, Baoding 071002, China
4 Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
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The two-dimensional electron gas (2DEG) generated at the LaAlO3/SrTiO3 interface has been in the focus of oxides research since its first discovery. Although oxygen vacancies play an important role in the generation of the insulator-to-metal transition of the SrTiO3 bare surface, their contribution at the LaAlO3/SrTiO3 interface remains unclear. In this work, we investigated a LaAlO3/SrTiO3 heterostructure with regional distribution of defect-based localized polar sites at the interface. Using static and time-resolved threshold photoemission electron microscopy, we prove that oxygen vacancies are induced near those polar sites, resulting in the increase of carrier density of the 2DEG states. In addition, oxygen-related surface states were uncovered, which we attributed to the release of lattice oxygen during the formation of oxygen vacancies. Such effects are mainly found spatially located around the defect sites at the buried interface, while other regions remain unaffected. Our results confirm that the itinerant electrons induced by oxygen vacancies can coexist with the charge transfer mechanism in the LaAlO3/SrTiO3 heterostructure, together leading to the formation of the metallic interface. These observations provide fundamental insights into the nature of LaAlO3/SrTiO3 interface based 2DEG and unique perspectives for potential applications.
two-dimensional electron gas photoemission electron microscopy strontium titanate defect states Opto-Electronic Science
2022, 1(7): 210011
Author Affiliations
Abstract
1 School of Information Engineering, Hebei University of Technology, Tianjin 300401, China
2 Hebei Key Lab of Optic-Electronic Information and Materials, College of Physics Science and Technology, Hebei University, Baoding 071002, China
Light-induced transverse thermoelectric effect is investigated in incline-oriented Bi2Sr2Co2Oy thin films covered with a graphite light absorption layer. Upon the illumination of a 980 nm cw laser, an enhanced voltage signal is detected and the improvement degree is found to be dependent on the thickness of the graphite layer. A two-dimensional (2D) heat transport model using the finite-difference method provides a reasonable explanation to the experimental data. Present results give some valuable instructions for the design of light absorption layers in this type of detector.
310.6845 Thin film devices and applications 040.5160 Photodetectors 230.4170 Multilayers Chinese Optics Letters
2015, 13(6): 063101
Author Affiliations
Abstract
Lateral photovoltaic (LPV) effects are observed in Bi2Sr2Co2Oy (BSCO) thin films. Upon illumination of a 532-nm constant laser, the lateral photovoltage is observed to vary linearly with the laser position between two electrodes on the film surface, and the position sensitivity can be enhanced by coating a layer of graphite on the surface of the BSCO film as a light absorber. Results suggest that the LPV effect in the thin film is independent of the photo-generated carriers but originates from thermoelectric effects. The present work demonstrates a potential application of BSCO films in position-sensitive photo (thermal) detectors.
310.6845 Thin film devices and applications 040.5160 Photodetectors 240.0310 Thin films Chinese Optics Letters
2013, 11(12): 123101
