氢在α-石英中扩散的从头算分子动力学

Ab Initio Molecular Dynamics calculations on hydrogen diffusion in α-quartz

采用从头算分子动力学研究在不同温度(300 K,700 K,1 000 K,1 200 K)下氢原子在α-石英中的扩散机制,根据爱因斯坦方程计算氢原子的扩散前项因子D0(7.72×10-4 cm2/s)和活化能(0.078 eV)。研究结果表明,氢原子在α-石英中的扩散路径有2种。低温下氢原子主要在由硅和氧原子组成的腔中做随机运动,直到跨过一个环到另外一个腔。同时研究温度在1 500 K时氢原子的扩散,氢在周围的3个氧原子之间发生跳跃,导致扩散过程中出现了3种缺陷结构,缺陷结构之间可以相互转化。本文研究在微电子器件可靠性分析等方面有应用价值。

The diffusion mechanism of hydrogen atom in α-quartz was investigated by using Ab Initio Molecular Dynamics(AIMD) under different temperatures(300 K,700 K,1 000 K,1 200 K) and the activation energy(0.078 eV) and pre-factor D0(7.72×10-4 cm2/s) were calculated by Einstein relation. The study demonstrates that there are two paths of diffusion of hydrogen atom in α-quartz. Under low temperatures, the hydrogen atom mainly moves in a network of cavities connected by silicon and oxygen atoms until it jumps from a ring to another cavity. In addition,the diffusion of hydrogen atom at 1 500 K has also been studied. The hydrogen jumps among the three oxygen atoms, resulting in three types of defect structures during the diffusion, which can be converted to each other. To clarify the diffusion mechanism of hydrogen atoms in quartz has important applications in reliability analysis of microelectronic devices.