Single-charge band-to-band tunneling via multiple-dopant clusters in nanoscale Si Esaki diodes

The electrostatic potential of p+-n+ junctions, as in Esaki (tunnel) diodes, originates from the Coulomb potentials of ionized dopants in the depletion-layer, but it has been modeled so far based on uniform space-charge regions, ignoring the discrete and random dopant distribution. This model can ex...

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Bibliographic Details
Published in:Applied physics letters 2019-06, Vol.114 (24)
Main Authors: Prabhudesai, Gaurang, Muruganathan, Manoharan, Anh, Le The, Mizuta, Hiroshi, Hori, Masahiro, Ono, Yukinori, Tabe, Michiharu, Moraru, Daniel
Format: Article
Language:English
Subjects:
Applied physics
Conduction bands
Depletion
Dopants
Numerical analysis
Transport
Tunnel diodes
Valence band
Variation
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Summary:The electrostatic potential of p+-n+ junctions, as in Esaki (tunnel) diodes, originates from the Coulomb potentials of ionized dopants in the depletion-layer, but it has been modeled so far based on uniform space-charge regions, ignoring the discrete and random dopant distribution. This model can explain well the band-to-band tunneling (BTBT) between the opposite bands of the quasineutral regions (conduction band in the n+-region and valence band in the p+-region). In this letter, we show that a BTBT transport model should contain the mechanism of tunneling via “inherent” localized bandgap-states, created by dopant-induced potential fluctuation, which becomes detectable as a parallel transport mechanism in nanoscale Esaki diodes. This is manifested by the observation of single-charge (SC) BTBT at 5.5 K in nanoscale Si Esaki diodes. Numerical analysis of nanoscale p+-n+ junctions with random dopant-atom distributions suggests that SC-BTBT is mediated by a potential dip created by a number of dopants “clustered” near each other, i.e., by a multiple-dopant cluster.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.5100342