标题： 沉积过程中温度激活扩散导致的致密膜到多孔膜的转变 显示英文标题

标题： Transition from compact to porous films in deposition with temperature activated diffusion

摘要： 我们研究了一个具有温度激活扩散的薄膜生长模型，允许形成悬垂结构和孔隙，但不包括吸附原子或团簇从沉积物上的脱离。在一维基底上对吸附原子单键的扩散与沉积比率R以及每个额外最近邻（NN）的脱离概率epsilon分别进行了模拟，其激活能分别为Es和Eb。如果R和epsilon独立变化，在0.075 < epsilon_c < 0.09范围内，低孔隙率和高孔隙率区域被分隔开，该点以下孔隙率几乎为零，而epsilon更大时则有有限的孔隙率。另一方面，对于固定Es和Eb并改变温度，孔隙率在Tc处有一个最小值，在该点以上观察到孔隙率随温度增加的非平凡区域。这与吸附原子的大迁移率有关，类似于平衡表面粗糙化的特征。在这个高温区域，由于不脱附条件，沉积物的结构类似于临界渗透簇。孔隙是由相应渗透骨架的块状物包围的区域，因此孔隙大小s的分布预计会按s^{-tau}的方式缩放，其中tau ~ 1.45，与数值估计结果合理一致。沉积物外界面的粗糙化表明在相变以下具有Villain-Lai-Das Sarma标度。在相变以上，粗糙指数alpha ~ 0.35 与渗透骨架结构一致，通过关系式alpha = 2-d_B，其中d_B是骨架分形维数。 显示英文摘要

摘要： We study a thin film growth model with temperature activated diffusion of adsorbed particles, allowing for the formation of overhangs and pores, but without detachment of adatoms or clusters from the deposit. Simulations in one-dimensional substrates are performed for several values of the diffusion-to-deposition ratio R of adatoms with a single bond and of the detachment probability epsilon per additional nearest neighbor (NN), respectively with activation energies are Es and Eb. If R and epsilon independently vary, regimes of low and high porosity are separated at 0.075 < epsilon_c < 0.09, with vanishingly small porosity below that point and finite porosity for larger epsilon. Alternatively, for fixed values of Es and Eb and varying temperature, the porosity has a minimum at Tc, and a nontrivial regime in which it increases with temperature is observe above that point. This is related to the large mobility of adatoms, resembling features of equilibrium surface roughening. In this high-temperature region, the deposit has the structure of a critical percolation cluster due to the non-desorption condition. The pores are regions enclosed by blobs of the corresponding percolating backbone, thus the distribution of pore size s is expected to scale as s^{-tau} with tau ~ 1.45, in reasonable agreement with numerical estimates. Roughening of the outer interface of the deposits suggests Villain-Lai-Das Sarma scaling below the transition. Above the transition, the roughness exponent alpha ~ 0.35 is consistent with the percolation backbone structure via the relation alpha = 2-d_B, where d_B is the backbone fractal dimension.