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Investigation of Coulomb stress changes in south Tibet(central Himalayas) due to the 25th April 2015 M_W 7.8 Nepal earthquake using a Coulomb stress transfer model

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Earthquake Science 2016年第5期29卷 271-279页

作者： Xu Cheng Guojie Meng Institute of Earthquake Science China Earthquake Administration

After Mw 7.8 Nepal earthquake occurred, the rearrangement of stresses in the crust commonly leads to subsequent damaging earthquakes. We present the calculations of the coseismic stress changes that resulted from the 25th April event using models of regional faults designed according to south Tibet-Nepal structure, and show that some indicative significant stress increases. We calculate static stress changes caused by the displacement of a fault on which dislocations happen and an earthquake occurs. A Mw 7.3 earthquake broke on 12 May at a distance of - 130 km SEE of the Mw 7.8 earthquake, whose focus roughly located on high Coulomb stress change （CSC） site. Aftershocks （first 15 days after the mainshock） are associated with stress increase zone caused by the main rupture. We set receiver faults with specified strikes, dips, and rakes, on which the stresses imparted by the source fault are resolved. Four group normal faults to the north of the Nepal earthquake seismogenic fault were set as receiver faults and variant results followed. We provide a discussion on Coulomb stress transfer for the seismogenic fault, which is useful to identify potential future rupture zones.

关键词： Coulomb stress changes elastic model Stress transfer Earthquake risk Nepal earthquake

Electron–acoustic phonon interaction and mobility in stressed rectangular silicon nanowires

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Chinese Physics B 2015年第1期24卷 411-417页

作者：朱林利 Department of Engineering Mechanics School of Aeronautics and Astronautics Zhejiang University

We investigate the effects of pre-stress and surface tension on the electron–acoustic phonon scattering rate and the mobility of rectangular silicon nanowires. With the elastic theory and the interaction Hamiltonian for the deformation potential, which considers both the surface energy and the acoustoelastic effects, the phonon dispersion relation for a stressed nanowire under spatial confinement is derived. The subsequent analysis indicates that both surface tension and pre-stress can dramatically change the electron–acoustic phonon interaction. Under a negative（positive） surface tension and a tensile（compressive） pre-stress, the electron mobility is reduced（enhanced） due to the decrease（increase） of the phonon energy as well as the deformation-potential scattering rate. This study suggests an alternative approach based on the strain engineering to tune the speed and the drive current of low-dimensional electronic devices.

关键词： phonon properties elastic model electron–acoustic phonon interaction carrier mobility

Influence of surface scattering on the thermal properties of spatially confined GaN nanofilm

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Chinese Physics B 2016年第8期25卷 301-307页

作者：侯阳朱林利 Department of Engineering Mechanics and Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang University

Gallium nitride（GaN）, the notable representative of third generation semiconductors, has been widely applied to optoelectronic and microelectronic devices due to its excellent physical and chemical properties. In this paper, we investigate the surface scattering effect on the thermal properties of GaN nanofilms. The contribution of surface scattering to phonon transport is involved in solving a Boltzmann transport equation（BTE）. The confined phonon properties of GaN nanofilms are calculated based on the elastic model. The theoretical results show that the surface scattering effect can modify the cross-plane phonon thermal conductivity of GaN nanostructures completely, resulting in the significant change of size effect on the conductivity in GaN nanofilm. Compared with the quantum confinement effect, the surface scattering leads to the order-of-magnitude reduction of the cross-plane thermal conductivity in GaN nanofilm. This work could be helpful for controlling the thermal properties of Ga N nanostructures in nanoelectronic devices through surface engineering.

关键词： GaN nanofilm elastic model quantum confinement Boltzmann transport equation size effect,phonon thermal conductivity

On the role of piezoelectricity in phonon properties and thermal conductivity of GaN nanofilms

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Theoretical & Applied Mechanics Letters 2016年第6期6卷 277-281页

作者： Linli Zhu Haonan Luo Department of Engineering Mechanics and Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang University

The effect of piezoelectricity on phonon properties and thermal conductivity of gallium nitride （GaN） nanofilms is theoretically investigated. The elasticity model is utilized to derive the phonon properties in spatially confined GaN nanofilms. The piezoelectric constitutive relation in GaN nanofilms is taken into account in calculating the phonon dispersion relation. The modified phonon group velocity and phonon density of state as well as the phonon thermal conductivity are also obtained due to the contribution of piezoelectricity. Theoretical results show that the piezoelectricity in GaN nanofilms can change significantly the phonon properties such as the phonon group velocity and density of states, resulting in the variation of the phonon thermal conductivity of GaN nanofilms remarkably. Moreover, the piezoelectricity of GaN can modify the dependence of thermal conductivity on the geometrical size and temperature. These results can be useful in modeling the thermal performance in the active region of GaN-based electronic devices.

关键词： GaN nanofilm Phonon properties elastic model Piezoelectricity Phonon thermal conductivity