Atomic-scale formation of ultrasmooth surfaces on sapphire substrates for high-quality thin-film fabrication

Abstract

The atomically ultrasmooth surfaces with atomic steps of sapphire substrates were obtained by annealing in air at temperatures between 1000 and 1400 °C. The terrace width and atomic step height of the ultrasmooth surfaces were controlled on an atomic scale by changing the annealing conditions and the crystallographic surface of substrates. The obtained ultrasmooth surface was stable in air. The topmost atomic structure of the terrace was examined quantitatively by atomic force microscopy and ion scattering spectroscopy as well as a theoretical approach using molecular dynamics simulations.

A Preparation Method for Atomically Clean Sapphire Surfaces and High Resolution Topographic Method for Their Imaging by Non-Contact Atomic Force Microscopy

“…We found that a small number of cycles of Ar + sputtering and annealing was sufficient to realize a clean Al 2 …”

“…Repeated iterations of Ar + sputtering and annealing are generally required to prepare a clean surface of TiO 2 (110) or other metal oxides. In the case of Al 2 O 3 (0001), however, we were able to achieve a periodic pattern of the Al 2 Keywords: sapphire, Al 2 O 3 (0001), non-contact atomic force microscopy, unit cell…”

Homoepitaxial growth of α-Al₂O₃ thin films on atomically stepped sapphire substrates by pulsed laser deposition at room-temperature

“…5) Prior to installing a substrate into the ultra-high vacuum PLD chamber, the substrate was cleaned with acetone and ethanol, and then dried in a stream of dry nitrogen.…”

“…1)4) In addition, atomically stepped sapphire substrates 5) have been applied for constructing nanostructures of inorganic materials 6), 7) and controlling molecular orientations of organic materials. 8) For high-performance mechanical, optical, and microelectronic applications, patterning the sapphire surface with features sized from the micrometer to nanometer scale is strongly desired.…”

Development of compact CW-IR laser deposition system for high-throughput growth of organic single crystals

“…• C for 5 h in air, they exhibited atomically flat surfaces [16]. The ILs were dropped with a micropipette (1 µl per droplet) on the substrates and no treatment was applied to spread them.…”