Initial growth dynamics of homo epitaxial (100) GaAs using pulsed laser deposition

The homoepitaxial pulsed laser deposition of GaAs on thermally desorbed (100) GaAs substrates is studied utilizing reflection high-energy electron diffraction and contact atomic force microscopy as a function of growth time. Interestingly, results indicate an unexpected initial roughening due to preferential growth on terrace regions around pits, resulting in a rough surface structure. As film growth proceeds, the surface structures become progressively more coherent up to a point, after which further growth results in smoothing by pit filling, and eventually resulting in an ordered undulatory surface topology. An explanation for this change in preferred growth region is set forth in which the initial oxide desorption process leaves regionally varying chemical stochiometries on the surface, which subsequently affect relative growth rates.