Long-range order in AlxGa1-xAs

We report the first observation of long-range order in a semiconductor III-V ternary alloy. AlxGa1-xAs thin crystals grown by metal-organic chemical vapor deposition or molecular-beam epitaxy have Ga atoms preferentially occupying the 0,0,0 and 0 sites and Al atoms the ,0, and 0 sites in each unit cell. Our results indicate that this ordered structure is the equilibrium state of AlxGa1-xAs. © 1985 The American Physical Society.