Abstract

Surface states are a classic obstacle in semiconductor technologies dating back to the John Bardeen era. We propose a generic approach, i.e., valence-mending passivation, to remove surface states. This paper reviews valence-mending passivation of the Si(1 0 0) surface, which is accomplished by depositing a monolayer of chalcogen atoms on Si(1 0 0). Methods for preparing an atomically-clean surface and depositing a self-limited monolayer of chalcogen atoms on Si(1 0 0) are developed in molecular beam epitaxy, solution passivation, and chemical vapor deposition. The passivated surface exhibits unprecedented electrical and chemical properties that are atypical of three-dimensional bulk semiconductors. The Schottky barrier heights for various metals now obey the Mott-Schottky theory on valence-mended Si(1 0 0). Metals of very-low and very-high workfunctions produce record-high and record-low Schottky barriers on the passivated surface. The record-high barrier demonstrated is 1.14 eV for an Al/sulfur-passivated p-type Si(1 0 0) junction, which exceeds the bandgap of Si. The record-low barrier is lower than 0.08 eV for an Al/sulfur-passivated n-type Si(1 0 0) junction and that barrier is likely negative at –0.02 eV. These record Schottky barriers show good thermal stability up to 500 °C upon annealing. Potential applications of valence-mending passivation include: (1) new approaches to Ohmic contacts for both heavily- and lightly-doped semiconductors, (2) a new diode that is an intermediate between a Schottky junction and a p-n junction, (3) suppressed surface and grain boundary recombination in optoelectronics and photovoltaics, and (4) the ideal substrate for van der Waals epitaxy of two-dimensional materials. The limitations of the current methods in characterizing extremely-low and negative Schottky barriers are outlined.

Original languageEnglish (US)
Pages (from-to)8-17
Number of pages10
JournalApplied Surface Science
Volume462
DOIs
StatePublished - Dec 31 2018

Fingerprint

Surface states
Passivation
Chalcogens
Semiconductor materials
Sulfur
Monolayers
Metals
Atoms
Ohmic contacts
Epitaxial growth
Molecular beam epitaxy
Optoelectronic devices
Chemical properties
Chemical vapor deposition
Grain boundaries
Diodes
Electric properties
Energy gap
Thermodynamic stability
Annealing

Keywords

  • Dangling bond
  • Metal/silicon junction
  • Schottky barrier
  • Selenium
  • Silicon (1 0 0) surface
  • Sulfur
  • Surface passivation
  • Surface state
  • Two-dimensional material

ASJC Scopus subject areas

  • Surfaces, Coatings and Films

Cite this

Removal of surface states on Si(1 0 0) by valence-mending passivation. / Tao, Meng.

In: Applied Surface Science, Vol. 462, 31.12.2018, p. 8-17.

Research output: Contribution to journalReview article

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abstract = "Surface states are a classic obstacle in semiconductor technologies dating back to the John Bardeen era. We propose a generic approach, i.e., valence-mending passivation, to remove surface states. This paper reviews valence-mending passivation of the Si(1 0 0) surface, which is accomplished by depositing a monolayer of chalcogen atoms on Si(1 0 0). Methods for preparing an atomically-clean surface and depositing a self-limited monolayer of chalcogen atoms on Si(1 0 0) are developed in molecular beam epitaxy, solution passivation, and chemical vapor deposition. The passivated surface exhibits unprecedented electrical and chemical properties that are atypical of three-dimensional bulk semiconductors. The Schottky barrier heights for various metals now obey the Mott-Schottky theory on valence-mended Si(1 0 0). Metals of very-low and very-high workfunctions produce record-high and record-low Schottky barriers on the passivated surface. The record-high barrier demonstrated is 1.14 eV for an Al/sulfur-passivated p-type Si(1 0 0) junction, which exceeds the bandgap of Si. The record-low barrier is lower than 0.08 eV for an Al/sulfur-passivated n-type Si(1 0 0) junction and that barrier is likely negative at –0.02 eV. These record Schottky barriers show good thermal stability up to 500 °C upon annealing. Potential applications of valence-mending passivation include: (1) new approaches to Ohmic contacts for both heavily- and lightly-doped semiconductors, (2) a new diode that is an intermediate between a Schottky junction and a p-n junction, (3) suppressed surface and grain boundary recombination in optoelectronics and photovoltaics, and (4) the ideal substrate for van der Waals epitaxy of two-dimensional materials. The limitations of the current methods in characterizing extremely-low and negative Schottky barriers are outlined.",
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AB - Surface states are a classic obstacle in semiconductor technologies dating back to the John Bardeen era. We propose a generic approach, i.e., valence-mending passivation, to remove surface states. This paper reviews valence-mending passivation of the Si(1 0 0) surface, which is accomplished by depositing a monolayer of chalcogen atoms on Si(1 0 0). Methods for preparing an atomically-clean surface and depositing a self-limited monolayer of chalcogen atoms on Si(1 0 0) are developed in molecular beam epitaxy, solution passivation, and chemical vapor deposition. The passivated surface exhibits unprecedented electrical and chemical properties that are atypical of three-dimensional bulk semiconductors. The Schottky barrier heights for various metals now obey the Mott-Schottky theory on valence-mended Si(1 0 0). Metals of very-low and very-high workfunctions produce record-high and record-low Schottky barriers on the passivated surface. The record-high barrier demonstrated is 1.14 eV for an Al/sulfur-passivated p-type Si(1 0 0) junction, which exceeds the bandgap of Si. The record-low barrier is lower than 0.08 eV for an Al/sulfur-passivated n-type Si(1 0 0) junction and that barrier is likely negative at –0.02 eV. These record Schottky barriers show good thermal stability up to 500 °C upon annealing. Potential applications of valence-mending passivation include: (1) new approaches to Ohmic contacts for both heavily- and lightly-doped semiconductors, (2) a new diode that is an intermediate between a Schottky junction and a p-n junction, (3) suppressed surface and grain boundary recombination in optoelectronics and photovoltaics, and (4) the ideal substrate for van der Waals epitaxy of two-dimensional materials. The limitations of the current methods in characterizing extremely-low and negative Schottky barriers are outlined.

KW - Dangling bond

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KW - Surface passivation

KW - Surface state

KW - Two-dimensional material

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