Abstract Surface morphology evolution of flat GaAs epitaxial layers grown on mesa structured substrates is studied under annealing in the presence of a saturated Ga-As melt. At high temperatures T > 700 °C, when the annealing conditions are shifted from the equilibrium towards sublimation, the initially flat surface roughens by unwinding spiral monatomic steps, which are induced by screw dislocations. This process leads to the formation of “inverted pyramid” spiral pits. Along with the spiral pits, the roughening consists in multilayer island formation on terraces, at the surface spots where the sublimation is inhibited. The mechanism of island formation is reproduced in the Monte Carlo simulation. The obtained data allowed us to estimate the relative undersaturation of −0.015 and Ga adatom diffusion length of 15 nm at T = 750 °C. Annealing at higher temperature T = 775 °C resulted in a peculiar “vortex”-like surface morphology, which consists in deep spiral pits covering the major part of the surface area.

中文翻译：

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通过在升华过程中解开位错诱导的螺旋原子台阶来热粗糙化 GaAs 表面

摘要 研究了在饱和 Ga-As 熔体存在下退火条件下在台面结构衬底上生长的平面 GaAs 外延层的表面形貌演变。在高温 T > 700 °C 下，当退火条件从平衡转变为升华时，最初平坦的表面通过螺旋位错引起的螺旋单原子步骤展开而变得粗糙。这个过程导致形成“倒金字塔”螺旋坑。与螺旋坑一起，粗糙化包括在平台上的多层岛形成，在升华被抑制的表面点。在蒙特卡罗模拟中重现了岛屿形成的机制。获得的数据使我们能够估计 -0.015 的相对不饱和度和 15 nm 的 Ga 吸附原子扩散长度在 T = 750 °C。