title: Determination of Young's Modulus of Ultrathin Nanomaterials.
abstract: Determination of the elastic modulus of nanostructures with sizes at several nm range is a challenge. In this study, we designed an experiment to measure the elastic modulus of amorphous Al2O3 films with thicknesses varying between 2 and 25 nm. The amorphous Al2O3 was in the form of a shell, wrapped around GaAs nanowires, thereby forming an effective core/shell structure. The GaAs core comprised a single crystal structure with a diameter of 100 nm. Combined in situ compression transmission electron microscopy and finite element analysis were used to evaluate the elastic modulus of the overall core/shell nanowires. A core/shell model was applied to deconvolute the elastic modulus of the Al2O3 shell from the core. The results indicate that the elastic modulus of amorphous Al2O3 increases significantly when the thickness of the layer is smaller than 5 nm. This novel nanoscale material can be attributed to the reconstruction of the bonding at the surface of the material, coupled with the increase of the surface-to-volume ratio with nanoscale dimensions. Moreover, the experimental technique and analysis methods presented in this study may be extended to measure the elastic modulus of other materials with dimensions of just several nanometers.
authors.forename: Yujie
authors.initials: Y
authors.lastname: Chen
authors.affiliation: ‡Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601, Australia.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Gao
authors.forename: Yanbo
authors.initials: Y
authors.lastname: Wang
authors.forename: Xianghai
authors.initials: X
authors.lastname: An
authors.forename: Xiaozhou
authors.initials: X
authors.lastname: Liao
authors.forename: Yiu-Wing
authors.initials: YW
authors.lastname: Mai
authors.affiliation: ‡Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601, Australia.
authors.forename: H Hoe
authors.initials: HH
authors.lastname: Tan
authors.affiliation: §Materials Engineering and Centre for Microscopy and Microanalysis, The University of Queensland, St Lucia, QLD 4072, Australia.
authors.forename: Jin
authors.initials: J
authors.lastname: Zou
authors.forename: Simon P
authors.initials: SP
authors.lastname: Ringer
authors.affiliation: ‡Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601, Australia.
authors.forename: Chennupati
authors.initials: C
authors.lastname: Jagadish
keywords: Young’s modulus; in situ deformation; size effect; transmission electron microscopy