Faceting, tricriticality, and attractive interactions between steps in the orientational phase diagram of silicon surfaces between [113] and [55 12]

• Published in: Surface science 1995-07, Vol.334 (1), p.153-169
• Main Authors: Song, S., Yoon, Mirang, Mochrie, S.G.J.
• Format: Article
• Language: English
• Subjects: Capillary waves; Equilibrium thermodynamics and statistical mechanics; Faceting; Silicon; Stepped single crystal surfaces; Surface structure; Surface thermodynamics; X-ray scattering, diffraction, and reflection
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(95)00491-2

An X-ray scattering study is presented of the orientational phase diagram of Si surfaces misoriented by up to 5.2° from the cubic [113] direction towards [111], and for temperatures between 300 and 1500 K. At the highest temperatures (above 1200 K), the surface is uniformly stepped. In this region, the intensity of near-specularly scattered X-rays increases with decreasing temperature, suggesting a corresponding increase in the surface roughness as a result of a direct attractive interaction between steps. For temperatures below a tricritical point of T′ t = 1200 K, there occurs a two-phase region in which (113) facets appear in coexistence with stepped phase regions. For temperatures below a triple point at T′ 3 = 1180 K, coexistence between (113) facets and (55 12) facets is found. These results pertain to the sample heating current directed towards [332̄]. For heating currents directed in the opposite direction, there occurs an electric-field-induced instability, which has a significant effect on the high-temperature morphology.