The Vacancy Effect on Thermal Interface Resistance between Aluminum and Silicon by Molecular Dynamics
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The Vacancy Effect on Thermal Interface Resistance between Aluminum and Silicon by Molecular Dynamics Yingying Zhang1#, Xin Qian1#, Zhan Peng1, Nuo Yang1* 1
School of Energy and Power Engineering, Huazhong University of Science and Technology
(HUST), Wuhan 430074, People's Republic of China
ABSTRACT Thermal transport across interfaces is an important issue for microelectronics, photonics, and thermoelectric devices and has been studied both experimentally and theoretically in the past. In this paper, thermal interface resistance (1/G) between aluminum and silicon with nanoscale vacancies was calculated using non-equilibrium molecular dynamics (NEMD). Both phonon-phonon coupling and electron-phonon coupling are considered in calculations. The results showed that thermal interface resistance increased largely due to vacancies. The effect of both the size and the type of vacancies is studied and compared. And an obvious difference is found for structures with different type/size vacancies. INTRODUCTION Interfacial thermal transport plays an important role for microelectronics, photonics, and thermoelectric devices where the devices reach nanoscale and have high interface densities[1, 2]. Recently, there are studies on the interfacial issue in experiment, theory and simulation. Since the acoustic mismatch model (AMM) and diffusive mismatch model (DMM) are limited in calculating the thermal conductance of ideal interface in cryogenic temperature[1, 2], the molecular dynamics (MD) simulation has become a popular method of predicting thermal boundary resistance in the last decade. The advantages of MD are that there is no assumption on phonon transmission mechanics and it includes the anharmonic effects and inelastic scatterings[3-5]. There are some calculations of the interfacial thermal conductance between semiconductor and metal. Cruz et al. calculated the thermal interface conductance of Au/Si at 300 K[6], and the value of 188 MW/m2-K is in good agreement with the measurement results with values ranging between 133 and 182 MW/m2-K[7]. Wang et al. calculated interfacial thermal conductance of Cu/Si with values around 400 MW/m2-K[8], which is much higher than experimental data[9]. Instead of an ideal interface, our recent work simulate a relaxed Al/Si interface with atomic level disorder by MD[10]. The value of thermal conductance is a little bit larger than the measurements. Interestingly, our results show that the localized ultra-high phonon modes, named as interface modes, emerge in disordered interface nanoscale region. That is, there is a novel and complex mechanism in the interfacial thermal transport.
More than two decades before, Swartz [1] predicted that the interface roughness would have effect on interfacial thermal transport. Recently, some experiments have shown the interface roughness, chemistry and structure could have a significant effect on thermal boundary conductance. Collins et. al. [11] presented experimentally that the surface chemistry affected the conductance between aluminum and diamond larg
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