Monte Carlo simulation of L1₁-type ordering due to surface step migration in the epitaxial growth of III--V semiconductor alloys

We investigated L1₁-type ordering due to surface step migration in III-V semiconductor alloys of (A_0.5B_0.5)^IIIC^V, using an Ising-like crystal growth model. A surface step along the [110] direction (the [110] step), which has a preference for unlike-atom pairs along the step, bears (111) and (111) variants (CuPt_B-type) of the four possible L1₁ variants. On the other hand, a surface step along the [110] direction (the [110] step), which has a preference for like-atom pairs, produces either of the two CuPt_B-type variants depending on the direction of the step motion. Antiphase boundaries are inserted parallel to (001) planes in the former case, and (111) or (111) in the latter case. The ordering rate in the case of the [110] step is larger than that for [110] step migration. These results explain well the previous experimental results obtained by transmission electron microscopy.