Scalable Patterning of One-Dimensional Dangling Bond Rows on Hydrogenated Si(001)

Silicon dangling bonds exposed on the monohydride silicon (001) (Si(001):H) surface are highly reactive, thus enabling site-selective absorption of atoms and single molecules into custom patterns designed through the controlled removal of hydrogen atoms. Current implementations of high-resolution hydrogen lithography on the Si(001):H surface rely on sequential removal of hydrogen atoms using the tip of a scanning probe microscope. Here, we present a scalable thermal process that yields very long rows of single dimer wide silicon dangling bonds suitable for self-assembly of atoms and molecules into one-dimensional structures of unprecedented length on Si(001):H. The row consists of the standard buckled Si dimer and an unexpected flat dimer configuration

Controlling the Atomic Layer Deposition of Titanium Dioxide on Silicon: Dependence on Surface Termination

Patterned fabrication depends on selective deposition that can be best achieved with atomic layer deposition (ALD). For the growth of TiO₂ by ALD using TiCl₄ and H₂O, X-ray photoelectron spectroscopy reveals a marked difference in growth on oxidized and hydrogen-terminated silicon surfaces, characterized by typical and predictable deposition rates observed on SiO₂ surfaces that can be 185 times greater than the deposition rates on hydrogen-terminated Si(100) and Si(111) surfaces. Large-scale patterning is demonstrated using wet chemistry, and nanometer-scale patterned TiO₂ growth is achieved through scanning tunneling microscopy (STM) tip-based lithography and ALD. The initial adsorption mechanisms of TiCl₄ on clean, hydrogen-terminated, and OH-terminated Si(100)-(2 × 1) surfaces are investigated in detail through density functional theory calculations. Varying the reactive groups on the substrate is found to strongly affect the probability of precursor nucleation on the surface during the ALD process. Theoretical studies provide quantitative understanding of the experimental differences obtained for the SiO₂, hydrogen-terminated, and clean Si(100) and Si(111) surfaces