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arXiv · 2305.18661

Local step-flow dynamics in thin film growth with desorption

Xiaozhi Zhang·Jeffrey G. Ulbrandt·Peco Myint·Andrei Fluerasu·Lutz Wiegart·Yugang Zhang·Christie Nelson·Karl F. Ludwig·Randall L. Headrick
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Abstract

Desorption of deposited species plays a role in determining the evolution of surface morphology during crystal growth when the desorption time constant is short compared to the time to diffuse to a defect site, step edge or kink. However, experiments to directly test the predictions of these effects are lacking. Novel techniques such as \emph{in-situ} coherent X-ray scattering can provide significant new information. Herein we present X-ray Photon Correlation Spectroscopy (XPCS) measurements during diindenoperylene (DIP) vapor deposition on thermally oxidized silicon surfaces. DIP forms a nearly complete two-dimensional first layer over the range of temperatures studied (40 - 120 $^{\circ}$C), followed by mounded growth during subsequent deposition. Local step flow within mounds was observed, and we find that there was a terrace-length-dependent behavior of the step edge dynamics. This led to unstable growth with rapid roughening ($\beta>0.5$) and deviation from a symmetric error-function-like height profile. At high temperatures, the grooves between the mounds tend to close up leading to nearly flat polycrystalline films. Numerical analysis based on a 1 + 1 dimensional model suggests that terrace-length dependent desorption of deposited ad-molecules is an essential cause of the step dynamics, and it influences the morphology evolution.

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Xiaozhi Zhang, Jeffrey G. Ulbrandt, Peco Myint, Andrei Fluerasu, Lutz Wiegart, Yugang Zhang, Christie Nelson, Karl F. Ludwig, Randall L. Headrick. 2023-05-29. Local step-flow dynamics in thin film growth with desorption. https://arxiv.org/abs/2305.18661

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