Reaction of aqueous ammonium sulfide on SiGe 25%

Stacy L. Heslop, Lauren Peckler, Anthony J Muscat

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

SiGe 25% substrates were treated with aqueous solutions of ammonium sulfide with and without added acid to understand the adsorption of sulfur on the surface. X-ray photoelectron spectroscopy showed no sulfide layer was deposited from aqueous (NH4)2S alone and instead both Si and Ge oxides formed during immersion in the sulfur solution. The addition of hydrofluoric and hydrochloric acids dropped the pH from 10 to 8 and deposited sulfides, yet increased the oxide coverage on the surface and preferentially formed Ge oxides. The sulfur coverage grew with increasing concentrations of acid in the aqueous (NH4)2S. The simultaneous deposition of O and S is suspected to be the result of oxidized sulfur species in solution. Metal-insulator-semiconductor capacitor (MISCAP) devices were fabricated to test the electrical consequences of aqueous ammonium sulfide wet chemistries on SiGe. MISCAPs treated with acidic ammonium sulfide solutions contained fewer interface defects in the valence band region. The defect density (Dit) was on the order of 10 + 12 cm-2 eV-1. The flat band voltage shift was lower after the acidic ammonium sulfide treatment, despite the presence of surface oxides. Adsorption of S and potentially O improved the stability of the surface and made it less electrically active.

Original languageEnglish (US)
Article number03E110
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Volume35
Issue number3
DOIs
StatePublished - May 1 2017

Fingerprint

Sulfur
Oxides
sulfides
Sulfides
sulfur
oxides
Hydrofluoric Acid
Adsorption
Acids
Hydrochloric Acid
Defect density
Valence bands
Hydrofluoric acid
acids
adsorption
Capacitors
X ray photoelectron spectroscopy
Metals
hydrochloric acid
hydrofluoric acid

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

Cite this

Reaction of aqueous ammonium sulfide on SiGe 25%. / Heslop, Stacy L.; Peckler, Lauren; Muscat, Anthony J.

In: Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films, Vol. 35, No. 3, 03E110, 01.05.2017.

Research output: Contribution to journalArticle

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