Comparative investigation of quantum-dot-like localization centers in InGaN quantum well and quantum dot structures

2005 ◽  
Vol 892 ◽  
Author(s):  
Kathrin Sebald ◽  
Henning Lohmeyer ◽  
Jürgen Gutowski ◽  
Tomohiro Yamaguchi ◽  
Detlef Hommel
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Quantum Well ◽  
Comparative Investigation ◽  
Emission Lines ◽  
Excitation Density ◽  
Spectral Position ◽  
Strong Localization ◽  
Experimental Findings

AbstractWe present comparative micro-photoluminescence measurements on InGaN/GaN quantum well and quantum dot samples. Single sharp emission lines were investigated for both kinds of samples as a function of temperature and excitation density. For the sharp emission lines of the quantum dots and the strong localization centers in the quantum well samples comparable experimental findings were obtained such as the independence of their spectral position of the excitation density and the observation of binding and antibinding multiexcitonic states giving clear evidence for the quantum dot nature of localization centers.

Micro-photoluminescence studies of excitonic and multiexcitonic states of quantum dot-like localization centers in InGaN/GaN structures

2004 ◽  
Vol 831 ◽  
Author(s):  
K. Sebald ◽  
H. Lohmeyer ◽  
J. Gutowski ◽  
S. Einfeldt ◽  
C. Roder ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Dot ◽  
Quantum Well ◽  
Emission Lines ◽  
Excitation Density ◽  
Spectral Position ◽  
Strong Localization ◽  
Photoluminescence Studies ◽  
Experimental Findings

ABSTRACTWe present micro-photoluminescence measurements on unstructured InGaN/GaN quantum well samples. Single sharp emission lines were observed and their optical properties were studied as a function of temperature and excitation density. The experimental findings such as the independence of their spectral position on the excitation density and the observation of binding and antibinding multiexcitonic states give clear evidence for the existence of strong localization centers in the InGaN quantum well, which exhibit the same characteristics as they are known for quantum dot structures.

ANOMALOUS SPECTRAL SHIFTS OF INDIRECT EXCITONS IN COUPLED GaAs QUANTUM WELLS

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3606-3610 ◽  
Author(s):  
D. W. SNOKE ◽  
V. NEGOITA ◽  
D. HACKWORTH ◽  
K. EBERL
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Low Frequency ◽  
Blue Shift ◽  
Substrate Material ◽  
Excitation Density ◽  
Spectral Position ◽  
Indirect Excitons ◽  
Spectral Shifts ◽  
Resonant Laser

We have studied the energy shifts of indirect excitons consisting of an electron in one quantum well and a hole in an adjacent quantum well. Several surprising effects occur: (1) a very strong blue shift with increasing intensity of resonant laser excitation, (2) a very strong red shift with weak magnetic field, and (3) very low-frequency (sub-Hz) fluctuations of the spectral position at high excitation density. We discuss the effect of screening by carriers excited in the substrate material.

INVESTIGATION OF CdTe QUANTUM DOTS SYNTHESIS TECHNOLOGY FEATURES IN COLLOID SOLUTIONS BY PHOTOLUMINESCENT SPECTROSCOPY AND SURFACE PLASMON RESONANCE REFRACTOMETRY

2020 ◽  
Vol 55 ◽  
pp. 126-135
Author(s):  
G.V. Dorozinsky ◽  
Keyword(s):  
Quantum Dots ◽  
Surface Plasmon Resonance ◽  
Quantum Dot ◽  
Cadmium Telluride ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Spectral Position ◽  
Colloidal Solutions ◽  
Spr Sensor ◽  
Pl Intensity

Effect of activation current variation in the synthesis of quantum dots (QD) of cadmium telluride in colloidal solutions on the change of emission spectra of photoluminescence (PL), the average size of QD and the change in the angular position of refractometric characteristics of surface plasmon resonance (SPR) was studied. The activation current was changed from 0.1 to 0.6 A in steps of 100 mA. For comparison, also performed the synthesis of cadmium telluride QD in colloidal solutions with a change in the duration of the synthesis in the range from 1 to 5 minutes in increments of 1 minute. The average QD size of cadmium telluride was determined by the peak values of the measured PL spectra of the corresponding colloidal solutions according to the modified Bruce formula. The response of the SPR sensor constructed according to the Kretschman scheme was defined as the angular shift of the minimum of the measured refractometric characteristics of the SPR when replacing deionized water with the studied colloidal solutions. The results of the study showed that the increase in the activation current in contrast to the increase in the duration of the synthesis led not only to a decrease in PL intensity, but also to its increase at low currents, which may be due to "electropolishing" of the quantum dot surface. Both technologies for the synthesis of quantum dots were characterized by the presence of slow growth processes, which was associated with the thermodynamics of nucleation processes and manifested in the form of saturation regions on the graphs of PL peak and minimum refractometric characteristics of SPR from synthesis duration and activation current. At different durations of quantum dot synthesis, a dependence (correlation coefficient -0.9992) was established between the response of the SPR sensor and the spectral position of the PL maximum, which was approximated by a linear function with a matching coefficient R 2 = 0.998. The results of the study showed that the use of variation of activation current in stabilizing the duration of synthesis is the dominant condition for creating high-emission light-emitting and light-converting semiconductor systems based on cadmium telluride QD, because with variation of activation current PL intensity was 431.9 abs., 4 times higher than for the case of variation in the duration of synthesis, namely 181.2 abs.one. The results of the study can be used to optimize the technology of manufacturing QD of cadmium telluride with predetermined characteristics.

Tuning Between Quantum-Dot- and Quantum-Well-Like Behaviors in Type II ZnTe Submonolayer Quantum Dots by Controlling Tellurium Flux During MBE Growth

2013 ◽  
Vol 42 (11) ◽  
pp. 3297-3302 ◽  
Author(s):  
H. Ji ◽  
B. Roy ◽  
S. Dhomkar ◽  
R. T. Moug ◽  
M. C. Tamargo ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Quantum Well ◽  
Type Ii ◽  
Mbe Growth

Improving the internal quantum efficiency of green InGaN quantum dots through coupled InGaN/GaN quantum well and quantum dot structure

2015 ◽  
Vol 8 (9) ◽  
pp. 094001 ◽  
Author(s):  
Jiadong Yu ◽  
Lai Wang ◽  
Di Yang ◽  
Zhibiao Hao ◽  
Yi Luo ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Quantum Well ◽  
Quantum Efficiency ◽  
Internal Quantum Efficiency

Optical Study of Carrier Transfer in Strain-induced Quantum Dots

1995 ◽  
Vol 417 ◽  
Author(s):  
Yitong Gu ◽  
M. D. Sturge ◽  
K. Kash ◽  
B. P. Van der Gaag ◽  
A. S. Gozdz ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Quantum Well ◽  
Barrier Height ◽  
Intermediate State ◽  
Excitation Transfer ◽  
Optical Study ◽  
Thermally Activated ◽  
Carrier Transfer

AbstractWe have studied excitation transfer from the host quantum well to strain-confined quantum dots. We find that there is a long-lived intermediate state acting as a reservoir, holding the excitation before it is thermally activated over a barrier to reach the quantum dot. The barrier height increases monotonically with dot size.

NiAg-graphene quantum dot-graphene hybrid with high oxidase-like catalytic activity for sensitive colorimetric detection of malathion

2021 ◽  
Author(s):  
Xu Dan ◽  
Ruiyi Li ◽  
Qinsheng Wang ◽  
Yongqiang Yang ◽  
Haiyan Zhu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Catalytic Activity ◽  
Quantum Dot ◽  
Colorimetric Detection ◽  
Graphene Quantum Dots ◽  
Functionalized Graphene ◽  
Graphene Quantum Dot ◽  
Nickel Silver

The paper reports the synthesis of nickel-silver-graphene quantum dot-graphene hybrid. Histidine-functionalized graphene quantum dots (His-GQDs) were bonded to graphene oxide (GO) and then combined with Ni2+ and Ag+ to form...

scholarly journals Effect of Growth Temperature on the Characteristics of CsPbI3-Quantum Dots Doped Perovskite Film

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4439
Author(s):  
Shui-Yang Lien ◽  
Yu-Hao Chen ◽  
Wen-Ray Chen ◽  
Chuan-Hsi Liu ◽  
Chien-Jung Huang
Keyword(s):  
Thin Films ◽  
Thermal Stability ◽  
Quantum Dots ◽  
Quantum Dot ◽  
Growth Temperature ◽  
Electron Mobility ◽  
Surface Defects ◽  
Different Temperatures ◽  
Pb Doping ◽  
Pristine Film

In this study, adding CsPbI3 quantum dots to organic perovskite methylamine lead triiodide (CH3NH3PbI3) to form a doped perovskite film filmed by different temperatures was found to effectively reduce the formation of unsaturated metal Pb. Doping a small amount of CsPbI3 quantum dots could enhance thermal stability and improve surface defects. The electron mobility of the doped film was 2.5 times higher than the pristine film. This was a major breakthrough for inorganic quantum dot doped organic perovskite thin films.

Carbon quantum dot-sensitized hollow TiO2 spheres for high-performance visible light photocatalysis

2021 ◽  
Author(s):  
Xianfeng Zhang ◽  
Zongqun Li ◽  
Shaowen Xu ◽  
Yaowen Ruan
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
High Performance ◽  
Carbon Quantum Dots ◽  
Visible Light Photocatalysis ◽  
Carbon Quantum Dot ◽  
Visible Light Photocatalytic

TiO2/CQD composites were synthesized through carbon quantum dots covalently attached to the surface of hollow TiO2 spheres for visible light photocatalytic degradation of organics.

scholarly journals Flexible and efficient perovskite quantum dot solar cells via hybrid interfacial architecture

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Long Hu ◽  
Qian Zhao ◽  
Shujuan Huang ◽  
Jianghui Zheng ◽  
Xinwei Guan ◽  
...  
Keyword(s):  
Thin Film ◽  
Quantum Dots ◽  
Solar Cells ◽  
Quantum Dot ◽  
High Performance ◽  
Mechanical Stability ◽  
Mechanical Adhesion ◽  
Perovskite Quantum Dots ◽  
Efficient Charge ◽  
Photovoltaic Technologies

AbstractAll-inorganic CsPbI3 perovskite quantum dots have received substantial research interest for photovoltaic applications because of higher efficiency compared to solar cells using other quantum dots materials and the various exciting properties that perovskites have to offer. These quantum dot devices also exhibit good mechanical stability amongst various thin-film photovoltaic technologies. We demonstrate higher mechanical endurance of quantum dot films compared to bulk thin film and highlight the importance of further research on high-performance and flexible optoelectronic devices using nanoscale grains as an advantage. Specifically, we develop a hybrid interfacial architecture consisting of CsPbI3 quantum dot/PCBM heterojunction, enabling an energy cascade for efficient charge transfer and mechanical adhesion. The champion CsPbI3 quantum dot solar cell has an efficiency of 15.1% (stabilized power output of 14.61%), which is among the highest report to date. Building on this strategy, we further demonstrate a highest efficiency of 12.3% in flexible quantum dot photovoltaics.

Sign in / Sign up

Export Citation Format

Share Document