Phase Transitions on Surfaces

他们将对相位进行实验和理论研究 硅和锗的邻位表面图。 最近 在他们的实验室的发展意味着， 具有重构相变是 邻面 这对我们的未来有着深远的影响。 因此对于许多先进装置 理念的 与重建相关的小面可能与 平衡晶体中锐边的形成 形状 利用热力学的论证，他们预测这种 在经历重建的表面上， 相变 因此，他们计划比较 一些相邻的硅和锗表面的示意图 自由能的唯象模型。 普遍 相图的特征，例如临界指数， 对这些模型施加了严格的限制。 非普遍的方面， 例如相位边界，可以用来设置 微观互动 相图的模拟将 测试现有的模型，并作为开发的指导方针 更准确的描述。 详细的相图 需要与理论进行比较，将使用 他们最近开发的高分辨率LEED仪器。

They will conduct an experimental and theoretical study of phase diagrams of vicinal surfaces of Silicon and Germanium. Recent developments in their laboratory imply that faceting associated with reconstructive phase transitions is a general property of vicinal surfaces. This has profound implications for the stability of vicinal surfaces and hence for many advanced device concepts. Faceting associated with reconstruction can be related to the formation of a sharp edge in the equilibrium crystal shape. Using thermodynamic arguments they predict that this kind of behavior is widespread on surfaces that undergo reconstructive phase transitions. They therefore plan to compare the phase diagrams of a number of vicinal Silicon and Germanium surfaces with phenomenological models of the free energy. Universal features of the phase diagrams, such as critical exponents, impose strong restrictions on such models. Nonuniversal aspects, such as phase boundaries, can be used to set limits on microscopic interactions. Simulations of the phase diagrams will test existing models and serve as a guideline for the development of more accurate descriptions. The detailed phase diagrams needed for comparison with the theory will be obtained using their recently developed high-resolution LEED instrument.