Pre-roughening induced deconstruction in Si and Ge(001) type crystal surfaces

Abstract

The (001) facets of Si and Ge have a uniaxial structure which changes direction at each mono-atomic step. This type of topology is unusual and new for the theory of surface roughening and reconstruction phase transitions. It can be incorporated into the solid-on-solid model description. The phase diagram includes pre-roughening transitions and disordered flat phases without the need for step - step interactions. The competition between this and the reconstruction in Si(001) can be described by a generalized 4-state clock-step model. This leads to the prediction that Si(001) and Ge(001) undergo a pre-roughening induced simultaneous deconstruction transition.