The formation of the ferroelectric domain structure as a result of irradiation by focused ion beam of[100]-cut 0.61Pb(Mg_(1/3)Nb_(2/3)TO_(3)–0.39PbTiO_(3)(PMN–PT)single crystals covered by surface artificial dielect...The formation of the ferroelectric domain structure as a result of irradiation by focused ion beam of[100]-cut 0.61Pb(Mg_(1/3)Nb_(2/3)TO_(3)–0.39PbTiO_(3)(PMN–PT)single crystals covered by surface artificial dielectric layer and with free surface was investigated.The dot irradiation resulted in formation of the wedge-like domains grown along[001]direction.For irradiation of the free surface,the domains are mainly located under the surface,while at the irradiated surface with an artificial dielectric layer the domains are located at the surface.It was shown that the subsurface wedge-shaped part of the domain is unstable and completely disappears after a month due to spontaneous backswitching under the action of the residual depolarization field.The revealed nonlinear dose dependence of the domain sizes was attributed to the distribution of the electric field using the point charge model.The domain interaction for the distance between irradiated dots below 30m has been revealed in all samples.It was shown that the decrease of the distance between irradiated dots in the created domain row leads to an increase in the length of the central domains,which is explained by the contribution of all injected charges to the switching field.展开更多
This paper presents an overview of the growth of Bi2Se3, a prototypical three-dimensional topological insulator, by molecular-beam epitaxy on various substrates. Comparison is made between the growth of Bi2 Se3 （111...This paper presents an overview of the growth of Bi2Se3, a prototypical three-dimensional topological insulator, by molecular-beam epitaxy on various substrates. Comparison is made between the growth of Bi2 Se3 （111） on van der Waals （vdW） and non-vdW substrates, with attention paid to twin suppression and strain. Growth along the [221] direction of Bi2Se3 on InP （001） and GaAs （001） substrates is also discussed.展开更多
Molecular beam epitaxy growth of GaAs on an offcut Ge （100） substrate has been systemically investigated. A high quality GaAs/Ge interface and CaAs film on Ge have been achieved. High temperature annealing before Ga...Molecular beam epitaxy growth of GaAs on an offcut Ge （100） substrate has been systemically investigated. A high quality GaAs/Ge interface and CaAs film on Ge have been achieved. High temperature annealing before GaAs deposition is found to be indispensable to avoid anti-phase domains. The quality of the GaAs film is found to strongly depend on the GaAs/Ge interface and the beginning of GaAs deposition. The reason why both high temperature annealing and GaAs growth temperature can affect epitaxial GaAs film quality is discussed. High quality InonTGao.s3As/GaAs strained quantum wells have also been achieved on a Ge substrate. Samples show flat surface morphology and narrow photoluminescence line width compared with the same structure sample grown on a GaAs substrate. These results indicate a large application potential for Ⅲ-Ⅴcompound semiconductor optoelectronic devices on Ge substrates.展开更多
基金the Ministry of Science and Higher Education of the Russian Federation(Project No.075-15-2021-1387)by the National Key R&D Program of China(Grant No.2021YFE0115000)+1 种基金the Ural Center for Shared Use“Modern nanotechnology”Ural Federal University(Reg.No.2968)supported by the Ministry of Science and Higher Education RF(Project No.075-15-2021-677)was used.
文摘The formation of the ferroelectric domain structure as a result of irradiation by focused ion beam of[100]-cut 0.61Pb(Mg_(1/3)Nb_(2/3)TO_(3)–0.39PbTiO_(3)(PMN–PT)single crystals covered by surface artificial dielectric layer and with free surface was investigated.The dot irradiation resulted in formation of the wedge-like domains grown along[001]direction.For irradiation of the free surface,the domains are mainly located under the surface,while at the irradiated surface with an artificial dielectric layer the domains are located at the surface.It was shown that the subsurface wedge-shaped part of the domain is unstable and completely disappears after a month due to spontaneous backswitching under the action of the residual depolarization field.The revealed nonlinear dose dependence of the domain sizes was attributed to the distribution of the electric field using the point charge model.The domain interaction for the distance between irradiated dots below 30m has been revealed in all samples.It was shown that the decrease of the distance between irradiated dots in the created domain row leads to an increase in the length of the central domains,which is explained by the contribution of all injected charges to the switching field.
文摘针对车载雷达多参数联合超分辨计算复杂度高、无法快速实现参数估计的问题,提出了基于频域波束降维的多参数联合超分辨算法。所提算法通过快速傅里叶变换(fast Fourier transform,FFT)将空时多参数域联合数据变换到频域,处理感兴趣区域的多维频域数据,完成空时波束空间降维和基于频域数据的多参数联合超分辨,实现目标信息的快速联合估计。推导了频域子空间正交性及频域波束降维超分辨算法理论。仿真研究了算法的分辨率和估计性能与信噪比的关系。仿真结果表明,所提算法的精度和分辨率远超传统FFT算法,相对于传统多重信号分类(multiple signal classification,MUSIC)算法,所提算法计算量大幅降低。
基金supported by the Research Grant Council (RGC) of Hong Kong Special Administrative Region for its financial support under the General Research Funds (Grant Nos. 706110 and 706111)the SRFDP and RGCERG Joint Research Scheme sponsored by the RGC of Hong Kong and the Ministry of Education of China (M-HKU709/l2)
文摘This paper presents an overview of the growth of Bi2Se3, a prototypical three-dimensional topological insulator, by molecular-beam epitaxy on various substrates. Comparison is made between the growth of Bi2 Se3 （111） on van der Waals （vdW） and non-vdW substrates, with attention paid to twin suppression and strain. Growth along the [221] direction of Bi2Se3 on InP （001） and GaAs （001） substrates is also discussed.
基金Project supported by the National Natural Science Foundation of China(Grant No.60625405)the National Basic Research Program of China(Grant Nos.2007CB936304 and 2010CB327601)
文摘Molecular beam epitaxy growth of GaAs on an offcut Ge （100） substrate has been systemically investigated. A high quality GaAs/Ge interface and CaAs film on Ge have been achieved. High temperature annealing before GaAs deposition is found to be indispensable to avoid anti-phase domains. The quality of the GaAs film is found to strongly depend on the GaAs/Ge interface and the beginning of GaAs deposition. The reason why both high temperature annealing and GaAs growth temperature can affect epitaxial GaAs film quality is discussed. High quality InonTGao.s3As/GaAs strained quantum wells have also been achieved on a Ge substrate. Samples show flat surface morphology and narrow photoluminescence line width compared with the same structure sample grown on a GaAs substrate. These results indicate a large application potential for Ⅲ-Ⅴcompound semiconductor optoelectronic devices on Ge substrates.
