High-Temperature Oxide Surface Preparation

SrTiO₃ crystal at 1300 °C in the deposition chamber. Each reflection in the double pane window is weaker than its lower neighbor by a factor of 600.
Atomic Force Microscopy (AFM) image of a SrTiO₃ surface prepared by high-temperature annealing. The terraces are covered by a uniform surface reconstruction as an ideal template for subsequent epitaxy.

Pulsed laser deposition and molecular beam epitaxy allow the synthesis of single crystalline layered structures with atomic scale dimensional control.
To reliably grow such structures with reproducible properties, a starting substrate surface with a highly perfect structure is required. Traditionally, oxide substrates are prepared for epitaxy using hydrofluoric acid etch and oven anneal steps before being loaded into the deposition system.
We have developed and characterized a process that replaces these steps by a single high-temperature anneal in the epitaxy chamber directly prior to deposition. This process produces surfaces that are equivalent or superior to the traditionally prepared surfaces. It is cleaner, faster, safer and better to control than the traditional procedure, thereby improving sample quality, reproducibility and throughput.

The process was enabled by the development of a new, powerful and efficient substrate heating system that allows us to access the entire temperature range up to the melting point of the substrates. It not only works for SrTiO₃, but also for many other substrate materials used in oxide epitaxy.

For more information see:
Appl. Phys. Lett. 112, 111601 (2018)

contact: Dr. Wolfgang Braun

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