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The strain relaxation of InAs/GaAs self-organized quantum dot

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Chinese Physics B 2009年第3期18卷 881-887页

作者：刘玉敏俞重远任晓敏 Institute of Optical Communication and Optoelectronics Beijing University of Posts and Telecommunications Key Laboratory of Optical Communication and Lightwave Technologies Ministry of Education(Beijing University of Posts and Telecommunications)

This paper presents a detailed analysis of the dependence of degree of strain relaxation of the self-organized InAs/GaAs quantum dot on the geometrical parameters. Differently shaped quantum dots arranged with different transverse periods are simulated in this analysis. It investigates the total residual strain energy that stored in the quantum dot and the substrate for all kinds of quantum dots with the same volume, as well as the dependence on both the aspect ratio and transverse period. The calculated results show that when the transverse period is larger than two times the base of the quantum dots, the influence of transverse periods can be ignored. The larger aspect ratio will lead more efficient strain relaxation. The larger angle between the faces and the substrate will lead more efficient strain relaxation. The obtained results can help to understand the shape transition mechanism during the epitaxial growth from the viewpoint of energy, because the strain relaxation is the main driving force of the quantum dot＇s self-organization.

关键词： quantum dot strain relaxation self-organization

Impact of strain relaxation on the growth rate of heteroepitaxial germanium tin binary alloy

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Journal of Semiconductors 2024年第10期45卷 35-41页

作者： Pedram Jahandar Maksym Myronov Department of Physics University of WarwickCoventryCV47ALUnited Kingdom

The growth of high-quality germanium tin(Ge_(1–y)Sn_(y))binary alloys on a Si substrate using chemical vapor deposition(CVD)techniques holds immense potential for advancing electronics and optoelectronics applications,including the development of efficient and low-cost mid-infrared detectors and light ***,achieving precise control over the Sn concentration and strain relaxation of the Ge_(1–y)Sn_(y)epilayer,which directly influence its optical and electrical properties,remain a significant *** this research,the effect of strain relaxation on the growth rate of Ge_(1–y)Sn_(y)epilayers,with Sn concentration>11at.%,is *** is successfully demonstrated that the growth rate slows down by~55%due to strain relaxation after passing its critical thickness,which suggests a reduction in the incorporation of Ge into Ge_(1–y)Sn_(y)growing *** the increase in Sn concentration as a result of the decrease in the growth rate,it has been found that the Sn incorporation rate into Ge_(1–y)Sn_(y)growing layers has also decreased due to strain *** valuable insights could offer a foundation for the development of innovative growth techniques aimed at achieving high-quality Ge_(1–y)Sn_(y)epilayers with tuned Sn concentration and strain relaxation.

关键词： GeSn germanium tin strain relaxation groupⅣsemiconductor chemical vapour deposition CVD

Impact of strain relaxation of AlGaN barrier layer on the performance of high Al-content AlGaN/GaN HEMT

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Science China(Technological Sciences) 2006年第4期49卷 393-399页

作者： YANG Yan HAO Yue ZHANG Jincheng WANG Chong FENG Qian Key Laboratory of the Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian UniversityXi'an 710071China

The effects of strain relaxation of AlGaN barrier layer on the conduction band profile,electron concentration and two-dimensional gas(2DEG)sheet charge density in a high Al-content AlGaN/GaN high electron mobility transistor(HEMT)are calculated by self-consistently solving Poisson’s and Schr?dinger’s *** effect of strain re-laxation on dc I-V characteristics of Al_(x)Ga_(1-x)N/GaN HEMT is obtained by developing a nonlinear charge-control model that describes the accurate relation of 2DEG sheet charge density and gate *** model predicts a highest 2DEG sheet charge density of 2.42×10^(13)cm^(-2)and maximum saturation current of 2482.8 mA/mm at a gate bias of 2 V for 0.7μm Al_(0.5)0Ga_(0.50)N/GaN HEMT with strain relaxation r=0 and 1.49×10^(13)cm^(-2)and 1149.7 mA/mm with strain relaxation r=*** comparison between simulations and physical measurements shows a good *** show that the effect of strain relaxation must be considered when analyzing the characteristics of high Al-content AlGaN/GaN HEMT theoretically,and the performance of the devices is improved by decreasing the strain relaxation of AlGaN barrier layer.

关键词： AlGaN/GaN high electron mobility transistor strain relaxation

Effects of the strain relaxation of an AlGaN barrier layer induced by various cap layers on the transport properties in AlGaN/GaN heterostructures

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Chinese Physics B 2011年第9期20卷 425-429页

作者：刘子扬张进成段焕涛薛军帅林志宇马俊彩薛晓咏郝跃 School of Microelectronics and State Key Discipline Laboratory of Wide Band Gap Semiconductor TechnologyXidian University

The strain relaxation of an A1GaN barrier layer may be influenced by a thin cap layer above, and affects the transport properties of A1GaN/GaN heterostructures. Compared with the slight strain relaxation found in A1GaN barrier layer without cap layer, it is found that a thin cap layer can induce considerable changes of strain state in the A1GaN barrier layer. The degree of relaxation of the A1GaN layer significantly influences the transport properties of the two-dimensional electron gas （2DEG） in A1GaN/GaN heterostructures. It is observed that electron mobility decreases with the increasing degree of relaxation of the A1GaN barrier, which is believed to be the main cause of the deterioration of crystalline quality and morphology on the A1GaN/GaN interface. On the other hand, both GaN and A1N cap layers lead to a decrease in 2DEC density. The reduction of 2DEG caused by the GaN cap layer may be attributed to the additional negative polarization charges formed at the interface between CaN and A1GaN, while the reduction of the piezoelectric effect in the A1GaN layer results in the decrease of 2DEC density in the case of A1N cap layer.

关键词： cap layer strain relaxation A1GaN/GaN transport properties

strain relaxation Related Photoluminescence Bands in Ge/Si Short Period Superlattices

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Semiconductor Photonics and Technology 1998年第2期4卷 89-93页

作者： JIZhenguo NoritakaUsami 等 ZhejiangUniversity Hangzhou310027CHN ResearchCenterforAdvancedScienceandTechnology UniversityofToky

Pure-Ge/Si short period superlattice (SPS) grown by gas source MBE (GSMBE) is studied by photoluminescence spectroscopy and Raman scattering spectroscopy. An abnormal band in photoluminescence is found in an intermediate range of Lsi between 1.9 nm-2.9 nm for samples with LGe fixed at 1.5 ml. In contrast to a pure-Ge/Si quantum well, the energy of the band shows red-shift as Lsi increases. Raman scattering shows that Si-Si vibration related Raman shift reaches a minimum for samples with strongest PL intensity of the abnormal band. It is therefore concluded that the abnormal band is related with strain relaxation process.

关键词： Photoluminescence Quantum Well Raman Scattering strain relaxation Superlattice

Possible abnormal mechanism for lattice strain relaxation in La0.7Ca0.3MnO3 thin film

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Possible abnormal mechanism for lattice strain relaxation in...

Stretchable alkenamides terminated Ti_(3)C_(2)T_(x)MXenes to release strain for lattice-stable mixed-halide perovskite solar cells with suppressed halide segregation

Ⅻ International Symposium on Small Particles and Inorganic Clusters

作者： W.S.Tan H.L.Cai X.S.Wu S.S.Jiang Q.J.Jia J.GaoDepartment of Applied Physics Nanjing University of Science and Technology Nanjing210094 P.R.China National Laboratory of Solid State Microstructures Department of Physics NanjingUniversity Nanjing 210093 P.R.China Institute of High Energy Physics Chinese Academy of Science Beijing 100039 P.R.China Department of Physics HongKong University HongKong PR.China

＜正＞ By the method of 90°off-axis radio frequency magnetron sputtering, La0.7Ca0.3MnO3 （LCMO） thin films with the thickness of 500 A were deposited on （001）-oriented single crystal substrates including SrTi03（STO）, MgO and sapphire（α-Al2O3, ALO）. Normal X-ray diffraction indicated high crystal qualities and well c-axis-orientation of samples LCMO/STO and LCMO/MgO, whereas LCMO/ALO film was polycrystalline. Grazing incidence X-ray

关键词： La0.7Ca0.3MnO3 film Grazing incidence X-ray diffraction strain relaxation In-plane lattice parameter

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Carbon Energy 2023年第12期5卷 21-30页

作者： Xuemei Yao Jialong Duan Yuanyuan Zhao Junshuai Zhang Qiyao Guo Qiaoyu Zhang Xiya Yang Yanyan Duan Peizhi Yang Qunwei Tang Institute of Carbon Neutrality College of Chemical and Biological EngineeringShandong University of Science and TechnologyQingdaoShandongChina Key Laboratory of Advanced Technique and Preparation for Renewable Energy Materials Ministry of EducationYunnan Normal UniversityKunmingYunnanChina College of Mechanical and Electronic Engineering Shandong University of Science and TechnologyQingdaoShandongChina College of Information Science and Technology Jinan UniversityGuangzhouGuangdongChina School of Materials Science and Engineering State Centre for International Cooperation on Designer Low-Carbon and Environmental Material(SCICDLCEM)Zhengzhou UniversityZhengzhouHenanChina

Bandgap-tunable mixed-halide perovskite materials have attracted considerable interest because of their indispensability as top counterparts in tandem solar ***,the soft and disordered lattice always suffers from severe phase segregation under illumination,which is particularly susceptible to residual lattice ***,we report a strain regulation strategy by using alkenamides terminated Ti_(3)C_(2)T_(x)MXenes as an additive into perovskite *** from the role of a template for grain growth to obtain high-quality films,the stretchable alkyl chain promotes lattice shrinkage or expansion to form an elastic grain boundary to eliminate the spatially distributed stain and shut down ion migration *** a result,the all-inorganic perovskite solar cells based on CsPbIBr_(2)and CsPbI_(2)Br halides achieve prolonged device stability under harsh conditions and the best power conversion efficiencies up to 11.06%and 14.30%,respectively.

关键词： all-inorganic perovskite solar cells defect passivation halide segregation stability strain relaxation

Fabrication of High Quality SiGe Virtual Substrates by Combining Misfit strain and Point Defect Techniques

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Tsinghua Science and Technology 2009年第1期14卷 62-67页

作者：梁仁荣王敬许军 Tsinghua National Laboratory for Information Science and Technology (TNList) Institute of Microelectronics Tsinghua University

High quality strain-relaxed thin SiGe virtual substrates have been achieved by combining the misfit strain technique and the point defect technique. The point defects were first injected into the coherently strained SiGe layer through the ＂inserted Si layer＂ by argon ion implantation. After thermal annealing, an in- termediate SiGe layer was grown with a strained Si cap layer. The inserted Si layer in the SiGe film serves as the source of the misfit strain and prevents the threading dislocations from propagating into the next epitaxial layer. A strained-SilSiGelinserted-SilSiGe heterostructure was achieved with a threading dislocation density of 1×10^4 cm-2 and a root mean square surface roughness of 0.87 nm. This combined method can effectively fabricate device-quality SiGe virtual substrates with a low threading dislocation density and a smooth surface.

关键词： strain relaxation point defects misfit strain SiGe virtual substrate strained Si inserted Si layer

Quasi-homoepitaxial GaN-based blue light emitting diode on thick GaN template

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Chinese Physics B 2014年第1期23卷 301-306页

作者：李俊泽陶岳彬陈志忠姜显哲付星星姜爽焦倩倩于彤军张国义 State Key Laboratory for Artificial Microstructures and Macroscopic Physics School of Physics Peking University Beijing 100871 China

The high power GaN-based blue light emitting diode(LED) on an 80-μm-thick GaN template is proposed and even realized by several technical methods like metal organic chemical vapor deposition(MOCVD), hydride vapor-phase epitaxial(HVPE), and laser lift-off(LLO). Its advantages are demonstrated from material quality and chip processing. It is investigated by high resolution X-ray diffraction(XRD), high resolution transmission electron microscope(HRTEM), Rutherford back-scattering(RBS), photoluminescence, current-voltage and light output-current measurements. The width of(0002) reflection in XRD rocking curve, which reaches 173 for the thick GaN template LED, is less than that for the conventional one, which reaches 258. The HRTEM images show that the multiple quantum wells(MQWs) in 80-μmthick GaN template LED have a generally higher crystal quality. The light output at 350 mA from the thick GaN template LED is doubled compared to traditional LEDs and the forward bias is also substantially reduced. The high performance of 80-μm-thick GaN template LED depends on the high crystal quality. However, although the intensity of MQWs emission in PL spectra is doubled, both the wavelength and the width of the emission from thick GaN template LED are increased. This is due to the strain relaxation on the surface of 80-μm-thick GaN template, which changes the strain in InGaN QWs and leads to InGaN phase separation.

关键词： homoepitaxy strain relaxation metal organic chemical vapor deposition(MOCVD) hydride vapor-phase epitaxy(HVPE)