Differential phase contrast (DPC) mapping electric fields: Optimising experimental conditions.
J Microsc
; 293(3): 177-188, 2024 Mar.
Article
em En
| MEDLINE
| ID: mdl-38353282
ABSTRACT
DPC in Scanning Transmission Electron Microscopy (STEM) is a valuable method for mapping the electric fields in semiconductor materials. However, optimising the experimental conditions can be challenging. In this paper, we test and compare critical experimental parameters, including the convergence angle, camera length, acceleration voltage, sample configuration, and orientation using a four-quadrant segmented detector and a Si specimen containing layers of different As concentrations. The DPC measurements show a roughly linear correlation with the estimated electric fields, until the field gets close to the detection limitation, which is â¼0.5 mV/nm with a sample thickness of â¼145 nm. These results can help inform which technique to use for different user cases When the electric field at a planar junction is above â¼0.5 mV/nm, DPC with a segmented detector is practical for electric field mapping. With a planar junction, the DPC signal-to-noise ratio can be increased by increasing the specimen thickness. However, for semiconductor devices with electric fields smaller than â¼0.5 mV/nm, or for devices containing curved junctions, DPC is unreliable and techniques with higher sensitivity will need to be explored, such as 4D STEM using a pixelated detector.
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MEDLINE
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En
Ano de publicação:
2024
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Article