热解碳化学气相沉积中的多重定态和非平衡相变的研究

Multiply steady states and nonequilibrium phase transition inchemical vapor deposition process

讨论在热解碳化学气相沉积过程中出现的多重定态和非平衡相变这一典型的非平衡物理现象的机理和发展趋势 .通过理论分析和实验结果的分析发现热解碳化学气相沉积的化学反应是一个典型的非平衡化学反应 ,其中在沉积过程中出现的生成碳黑的过程是一个典型的非平衡相变 .在这一非平衡化学反应中 ,自由基的反应模型符合Schlogl模型 .在这一非平衡化学反应中 ,有线性区和非线性区 ,线性区的产物是热解碳 ,而非线性区是碳黑 .在线性区 ,反应速率方程是唯一的、线性的 ,而在非线性区 ,反应速率方程是多重的、非线性的 .

This paper is mainly concerned with the mechanism to produce multi-states and nonequilibrum phase transition in chemical vapor deposition (CVD) process. It was discovered that the polymerization reaction in CVD process is a typical nonequilibrum chemical reaction with a bifurcation structure and its steady state model of free radical is fit to the Schlogl model through carefully analyzing the mechanism and experimental results. There are linear and nonlinear areas in the nonequilibrum reaction system, and there is a nonequilibrum phase transition between the two areas. The CVD product in the linear area is different from that in the nonlinear area. The product in the linear area is pyrocarbon and that in the nonlinear area is the carbon black. Further study reveals that the function of deposition rate is linear and has only one formula when the CVD reaction system is in the linear area. But the function of deposition rate will be nonlinear, has multi-solutions and generates a bifurcation structure when the system goes into the nonlinear area. With the reaction condition being far from the equilibrium, the CVD reaction system will select the steady state branch that is far from equilibrium.