TY - JOUR
T1 - Atomic resolution phase contrast imaging and in-line holography using variable voltage and dose rate
AU - Barton, Bastian
AU - Jiang, Bin
AU - Song, Cheng Yu
AU - Specht, Petra
AU - Calderon, Hector
AU - Kisielowski, Christian
PY - 2012/10
Y1 - 2012/10
N2 - The TEAM 0.5 electron microscope is employed to demonstrate atomic resolution phase contrast imaging and focal series reconstruction with acceleration voltages between 20 and 300 kV and a variable dose rate. A monochromator with an energy spread of ≤0.1 eV is used for dose variation by a factor of 1,000 and to provide a beam-limiting aperture. The sub-Ångstrøm performance of the instrument remains uncompromised. Using samples obtained from silicon wafers by chemical etching, the [200] atom dumbbell distance of 1.36 Å can be resolved in single images and reconstructed exit wave functions at 300, 80, and 50 kV. At 20 kV, atomic resolution <2 Å is readily available but limited by residual lens aberrations at large scattering angles. Exit wave functions reconstructed from images recorded under low dose rate conditions show sharper atom peaks as compared to high dose rate. The observed dose rate dependence of the signal is explained by a reduction of beam-induced atom displacements. If a combined sample and instrument instability is considered, the experimental image contrast can be matched quantitatively to simulations. The described development allows for atomic resolution transmission electron microscopy of interfaces between soft and hard materials over a wide range of voltages and electron doses.
AB - The TEAM 0.5 electron microscope is employed to demonstrate atomic resolution phase contrast imaging and focal series reconstruction with acceleration voltages between 20 and 300 kV and a variable dose rate. A monochromator with an energy spread of ≤0.1 eV is used for dose variation by a factor of 1,000 and to provide a beam-limiting aperture. The sub-Ångstrøm performance of the instrument remains uncompromised. Using samples obtained from silicon wafers by chemical etching, the [200] atom dumbbell distance of 1.36 Å can be resolved in single images and reconstructed exit wave functions at 300, 80, and 50 kV. At 20 kV, atomic resolution <2 Å is readily available but limited by residual lens aberrations at large scattering angles. Exit wave functions reconstructed from images recorded under low dose rate conditions show sharper atom peaks as compared to high dose rate. The observed dose rate dependence of the signal is explained by a reduction of beam-induced atom displacements. If a combined sample and instrument instability is considered, the experimental image contrast can be matched quantitatively to simulations. The described development allows for atomic resolution transmission electron microscopy of interfaces between soft and hard materials over a wide range of voltages and electron doses.
KW - aberration-corrected TEM
KW - exit wave reconstruction
KW - focal series
KW - high-resolution TEM
KW - in-line electron holography
KW - lattice phonons
KW - low dose TEM
KW - low voltage TEM
KW - monochromator
UR - http://www.scopus.com/inward/record.url?scp=84864837009&partnerID=8YFLogxK
U2 - 10.1017/S1431927612001213
DO - 10.1017/S1431927612001213
M3 - Artículo
C2 - 23083920
SN - 1431-9276
VL - 18
SP - 982
EP - 994
JO - Microscopy and Microanalysis
JF - Microscopy and Microanalysis
IS - 5
ER -