Tadayyon-Eslami T, Kan H-C, Calhoun L C, Phaneuf R J
Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA.
Phys Rev Lett. 2006 Sep 22;97(12):126101. doi: 10.1103/PhysRevLett.97.126101. Epub 2006 Sep 18.
We observe a dramatic change in the unstable growth mode during GaAs molecular beam epitaxy on patterned GaAs(001) as the temperature is lowered through approximately 540 degrees C, roughly coincident with the preroughening temperature. Observations of the As2 flux dependence, however, rule out thermodynamic preroughening as driving the growth mode change. Similar observations rule out the change in surface reconstruction as the cause. Instead, we find evidence that the change in the unstable growth mode can be explained by a competition between the decreased adatom collection rate on small terraces and a small anisotropic barrier to adatom diffusion downward across step bunches.
我们观察到，在图案化的GaAs(001)上进行GaAs分子束外延生长时，当温度降低至约540摄氏度（大致与预粗糙化温度一致）时，不稳定生长模式发生了显著变化。然而，对As2通量依赖性的观察排除了热力学预粗糙化是导致生长模式变化的原因。类似的观察也排除了表面重构变化是其原因。相反，我们发现有证据表明，不稳定生长模式的变化可以通过小台面上吸附原子收集速率的降低与吸附原子向下穿过台阶束扩散的小各向异性势垒之间的竞争来解释。
