Long-range order in thick, unstrained Si0.5Ge0.5 epitaxial layers

We observe, for the first time, long-range order in thick, unstrained SiGe alloys, with and without boron doping. This ordering occurs along the four equivalent 111 directions. The ordered domains are randomly shaped, and corresponds to alternating double layers of Si and Ge. Bond energy arguments are used to explain the formation of this new phase. © 1990 The American Physical Society.