Resolving and tuning carrier capture rates at a single silicon atom gap state

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DOIResolve DOI: https://doi.org/10.1021/acsnano.7b07068
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Name affiliation
  1. National Research Council of Canada. Nanotechnology
FormatText, Article
Subjectcarrier-capture rates; dangling bonds; noncontact atomic force microscopy; silicon; time-resolved scanning tunneling microscopy
Abstract
We report on tuning the carrier capture events at a single dangling bond (DB) midgap state by varying the substrate temperature, doping type, and doping concentration. All-electronic time-resolved scanning tunneling microscopy (TR-STM) is employed to directly measure the carrier capture rates on the nanosecond time scale. A characteristic negative differential resistance (NDR) feature is evident in the scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) measurements of DBs on both n- and p-type doped samples. We find that a common model accounts for both observations. Atom-specific Kelvin probe force microscopy (KPFM) measurements confirm the energetic position of the DB’s charge transition levels, corroborating STS studies. We show that under different tip-induced fields the DB can be supplied with electrons from two distinct reservoirs: the bulk conduction band and/or the valence band. We measure the filling and emptying rates of the DBs in the energy regime where electrons are supplied by the bulk valence band. We show that adding point charges in the vicinity of a DB shifts observed STS and NDR features due to Coulombic interactions.
Publication date
PublisherACS
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  • ACS Nano.
LanguageEnglish
Peer reviewedYes
NPARC number23002433
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Record identifierb681fbd1-f23a-452f-b3de-d297f86471a9
Record created2017-11-10
Record modified2020-05-30
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