摘要
针对分子动力学模拟存在的缺点,提出了基于晶格动力学模拟纳米薄膜热特性的新方法,并用该方法模拟了各种不同厚度的硅和氩纳米薄膜的比热、熔化温度、热膨胀系数和热传导系数等热特性参数。计算结果表明纳米薄膜具有与宏观晶体不同的热特性,并且呈现随纳米薄膜厚度变化的尺寸效应:纳米薄膜越薄,则熔化温度越低、比热越大、面向热膨胀系数越大、法向热传导系数越小;当纳米薄膜厚度远小于相应的宏观晶体的声子平均自由程时,法向热传导系数远小于相应的宏观晶体的热传导系数,并与纳米薄膜厚度成正比。
To overcome the drawbacks of molecular dynamics simulation, a new approach based on lattice dynamics to simulate the thermal properties of nanofilms was put forward, and was applied to simulate the thermal property parameters, such as the specific heat capacities, melting temperatures, thermal expansion coefficients and thermal conductivities of silicon and argon nanofilms with different thicknesses . The calculating results show that nanofilms have different thermal properties from the corresponding bulk crystal and appear thickness size effects on thermal properties. The thinner nanofilm has lower melting point, larger specific heat capacity, larger thermal expansion coefficient in the in-plane direction and smaller thermal conductivity in the cross-plane direction than the thicker film, and the thermal conductivity of nanofilm in the crossplane direction is in direct proportion to the thickness of nanofilm when the thickness of nanofilm is much smaller than the phonon mean free path of the corresponding bulk crystal.
出处
《微纳电子技术》
CAS
2008年第5期249-254,共6页
Micronanoelectronic Technology
基金
国家自然科学基金资助项目(5375154)
关键词
微/纳机电系统
纳米薄膜
晶格动力学
热特性
尺寸效应
micro/nano electromechanical system （M/NEMS）
nanofilm
lattice dynamics
thermal property
size effect
