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Title: Thickness Determination of Few-Layer Hexagonal Boron Nitride Films by Scanning Electron Microscopy and Auger Electron Spectroscopy

Authors:
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1165693
Report Number(s):
BNL-107102-2014-JA
R&D Project: 16080/16080; KC0403020
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: APL Materials; Journal Volume: 2
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Sutter P. Thickness Determination of Few-Layer Hexagonal Boron Nitride Films by Scanning Electron Microscopy and Auger Electron Spectroscopy. United States: N. p., 2014. Web. doi:10.1063/1.4889815.
Sutter P. Thickness Determination of Few-Layer Hexagonal Boron Nitride Films by Scanning Electron Microscopy and Auger Electron Spectroscopy. United States. doi:10.1063/1.4889815.
Sutter P. Wed . "Thickness Determination of Few-Layer Hexagonal Boron Nitride Films by Scanning Electron Microscopy and Auger Electron Spectroscopy". United States. doi:10.1063/1.4889815.
@article{osti_1165693,
title = {Thickness Determination of Few-Layer Hexagonal Boron Nitride Films by Scanning Electron Microscopy and Auger Electron Spectroscopy},
author = {Sutter P.},
abstractNote = {},
doi = {10.1063/1.4889815},
journal = {APL Materials},
number = ,
volume = 2,
place = {United States},
year = {Wed Jul 16 00:00:00 EDT 2014},
month = {Wed Jul 16 00:00:00 EDT 2014}
}
  • We assess scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) for thickness measurements on few-layer hexagonal boron nitride (h-BN), the layered dielectric of choice for integration with graphene and other two-dimensional materials. Observations on h-BN islands with large, atomically flat terraces show that the secondary electron intensity in SEM reflects monolayer height changes in films up to least 10 atomic layers thickness. From a quantitative analysis of AES data, the energy-dependent electron escape depth in h-BN films is deduced. The results show that AES is suitable for absolute thickness measurements of few-layer h-BN of 1 to 6 layers.
  • Characterization of the structural and physical properties of two-dimensional (2D) materials, such as layer number and inelastic mean free path measurements, is very important to optimize their synthesis and application. In this study, we characterize the layer number and morphology of hexagonal boron nitride (h-BN) nanosheets on a metallic substrate using field emission scanning electron microscopy (FE-SEM) and scanning helium ion microscopy (HIM). Using scanning beams of various energies, we could analyze the dependence of the intensities of secondary electrons on the thickness of the h-BN nanosheets. Based on the interaction between the scanning particles (electrons and helium ions) andmore » h-BN nanosheets, we deduced an exponential relationship between the intensities of secondary electrons and number of layers of h-BN. With the attenuation factor of the exponential formula, we calculate the inelastic mean free path of electrons and helium ions in the h-BN nanosheets. Our results show that HIM is more sensitive and consistent than FE-SEM for characterizing the number of layers and morphology of 2D materials.« less
  • Al films deposited on Nb can be oxidized and used to make Josephson junction devices. We studied the structure of Al films deposited under ''warm'' (estimated to be near 200 /sup 0/C) and ''cold'' (near room temperature) conditions because the cold films produced better Josephson junction devices. For the warm case, the Al film was composed of islands with open channels between them, which we attribute to a high mobility of the Al atoms that lowers the island nucleation density. The Nb surface was extremely flat, which we ascribe to the high surface atom mobility at the higher deposition temperature.more » The cold Al film was of uniform thickness which can be explained by a high island nucleation density. The cold Nb films had an undulating surface, caused by the lack of surface atom mobility during deposition. There was no evidence of Al-Nb interdiffusion, even after postdeposition heating to 300 /sup 0/C. Auger spectroscopy, transmission electron microscopy, and scanning electron microscopy were needed to obtain these definitive conclusions.« less