Si2H6 Dissociative Chemisorption and Dissociation on Si(100)-(2脳1) and Ge(100)-(2脳1)

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• 作者：Jean-Francois Veyan ; Heesung Choi ; Min Huang ; R.C. Longo ; Josh B. Ballard ; Stephen McDonnell ; Manori P. Nadesalingam ; Hong Dong ; Irinder S. Chopra ; James H. G. Owen ; Wiley P. Kirk ; John N. Randall ; Robert M. Wallace ; Kyeongjae Cho ; Yves J. Chabal
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：December 22, 2011
• 年：2011
• 卷：115
• 期：50
• 页码：24534-24548
• 全文大小：1491K
• 年卷期：v.115,no.50(December 22, 2011)
• ISSN：1932-7455

文摘

Atomically controlled epitaxy of semiconductor-on-semiconductor is important for the construction of nanometer-scale devices such as quantum dots, qubits for quantum computing, nanoelectromechanical systems (NEMS) oscillators, and nanobiomedical devices. For instance, patterned atomic layer epitaxy (ALE) using a scanning tunneling microscopy tip to depassivate an area of a H-terminated Si(001) surface, creating a pattern for subsequent Si growth, should lead to a new generation of atomically precise structures. Vapor phase epitaxy is well-suited to achieve controlled deposition, as the precursors are not reactive with the H-terminated background, unlike Si atoms from solid-source evaporation. Disilane (Si₂H₆) is arguably the best precursor for Si ALE on Si or Ge surfaces at moderate temperatures; yet, its adsorption configuration and subsequent decomposition pathways are not well understood. Combining experimental data from in situ infrared absorption spectroscopy (IRAS), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS) after saturation by disilane of both Si(100)-(2脳1) and Ge(100)-(2脳1) surfaces, with first-principles calculations of candidate surface structures, we show that Si₂H₆ chemisorbs through a 尾-hydride elimination pathway as Si₂H₅ and H, instead of the previously proposed SiH₃, and subsequently decomposes into an ad-monohydride dimer. The initial chemisorption process takes place on a single dimer and produces a monohydride ad-dimer oriented perpendicular to the substrate dimer rows. The ad-dimer can be located either in between two adjacent, initially clean dimers from the same dimer row, or in a bridging position over the trench between two adjacent dimer rows. These findings provide clear guidance for the formation of atomic size structures defined by local removal of hydrogen on H-terminated Si surfaces.