Heterogeneous nucleation of pits via step pinning during Si(100) homoepitaxy

Abstract

Using scanning tunneling microscopy (STM), we investigate oxide-induced growth pits in Si thin films deposited by molecular beam epitaxy. In the transition temperature range from 2D adatom islanding to step-flow growth, systematic controlled air leaks into the growth chamber induce pits in the growth surface. We show that pits are also correlated with oxygen-contaminated flux from Si sublimation sources. From a thermodynamic standpoint, multilayer growth pits are unexpected in relaxed homoepitaxial growth, whereas oxidation is a known cause for step pinning, roughening, and faceting on elemental surfaces, both with and without growth flux. Not surprisingly, pits are thermodynamically metastable and heal by annealing to recover a smooth periodic step arrangement. STM reveals new details about the pits' atomistic origins and growth dynamics. We give a model for heterogeneous nucleation of pits by preferential adsorption of Å-sized oxide nuclei at intrinsic growth antiphase boundaries, and subsequent step pinning and bunching around the nuclei.

arXiv comment9 pages, 5 figures

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• Silicon Quantum Electronics
• Exchange in silicon-based quantum computer architecture
• Instabilities in crystal growth by atomic or molecular beams
• Controllable valley splitting in silicon quantum devices
• Theory of valley-orbit coupling in a Si/SiGe quantum dot
• Interface roughness, valley-orbit coupling and valley manipulation in quantum dots
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Cited by in corpus (2)

• Utilizing multimodal microscopy to reconstruct Si/SiGe interfacial atomic disorder and infer its impacts on qubit variability
• Atomic-layer doping of SiGe heterostructures for atomic-precision donor devices