Assessment of Active Dopants and p-n Junction Abruptness Using In Situ Biased 4D-STEM.
basic_science · Level V
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- Record sourced from PubMed, PMID 36442685.
- Also identified by DOI 10.1021/acs.nanolett.2c03684.
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Abstract
A key issue in the development of high-performance semiconductor devices is the ability to properly measure active dopants at the nanometer scale. In a p-n junction, the abruptness of the dopant profile around the metallurgical junction directly influences the electric field. Here, a contacted nominally symmetric and highly doped (<i>N</i><sub><i>A</i></sub> = <i>N</i><sub><i>D</i></sub> = 9 × 10<sup>18</sup> cm<sup>-3</sup>) silicon p-n specimen is studied through in situ biased four-dimensional scanning transmission electron microscopy (4D-STEM). Measurements of electric field, built-in voltage, depletion region width, and charge density are combined with analytical equations and finite-element simulations in order to evaluate the quality of the junction interface. It is shown that all the junction parameters measured are compatible with a linearly graded junction. This hypothesis is also consistent with the evolution of the electric field with bias as well as off-axis electron holography data. These results demonstrate that in situ biased 4D-STEM can allow a better understanding of the electrostatics of semiconductor p-n junctions with nm-scale resolution.