Title: In-situ quantification of the surface roughness for facile fabrications of atomically smooth thin films

Journal Article · · Nano Research
 [1];  [2];  [1];  [3];  [1];  [1];  [2];  [2];  [1]
  1. Univ. of Science and Technology of China, Hefei (China); ShanghaiTech Univ. (China)
  2. ShanghaiTech Univ. (China)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
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Here in this work we present an in-situ technique to quantify the layer-by-layer roughness of thin films and heterostructures by measuring the spectral profile of the reflection high-energy electron diffraction (RHEED). The characteristic features of the diffraction spot, including the vertical to lateral size ratio c/b and the asymmetrical ratio c1/c2 along the vertical direction, are found to be quantitatively dependent on the surface roughness. The quantitative relationships between them are established and discussed for different incident angles of high-energy electrons. As an example, the surface roughnesses of LaCoO3 films grown at different temperatures are obtained using such an in-situ technique, which are confirmed by the ex-situ atomic force microscopy. Moreover, the in-situ measured layer-by-layer roughness oscillations of two LaCoO3 films are demonstrated, revealing drastically different information from the intensity oscillations. The experiments assisted with the in-situ technique demonstrate an outstanding high resolution down to similar to ~0.1 Å. Therefore, the new quantitative RHEED technique with real-time feedbacks significantly escalates the thin film synthesis efficiency, especially for achieving atomically smooth surfaces and interfaces. It opens up new prospects for future generations of thin film growth, such as the artificial intelligence-assisted thin film growth.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Organization:
Fundamental Research Funds for the Central Universities; National Key Research and Development Program of China; National Science Foundation of China; USDOE
Grant/Contract Number:
AC02-06CH11357
OSTI ID:
1848086
Journal Information:
Nano Research, Journal Name: Nano Research Journal Issue: 2 Vol. 15; ISSN 1998-0124
Publisher:
SpringerCopyright Statement
Country of Publication:
United States
Language:
English

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77 NANOSCIENCE AND NANOTECHNOLOGY
high efficiency
high-energy electron diffraction
in-situ
real time
reflection
roughness
thin film growth