Quantitative analysis of chemical interaction and doping of the Si(111) native oxide surface with tetrafluorotetracyanoquinodimethane

Journal Article · Mon Apr 14 04:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4871402· OSTI ID:22273595

Yoshimoto, Shinya; Furuhashi, Masayuki; Koitaya, Takanori; Shiozawa, Yuichiro; Fujimaki, Kazutaka; Harada, Yosuke; Mukai, Kozo; Yoshinobu, Jun ^[1]

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1. The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

The charge-transfer states and the carrier concentration of the native oxide Si(111) surface adsorbed with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F{sub 4}-TCNQ) were investigated by X-ray photoelectron spectroscopy (XPS) and independently driven four-probe electrical conductivity measurements. The XPS results show that F{sub 4}-TCNQ molecules are involved in charge transfer with the SiO{sub 2}/Si(111) surface. The Si 2p XPS spectra and the surface photovoltage shift provide the evidences of (i) change in the oxidation states at the SiO{sub 2}-Si(111) interface region and (ii) formation of a p-type space charge layer (SCL) with a hole concentration of 1.7 × 10{sup 10} cm{sup −2}, respectively. The four-probe I–V measurements also support the formation of the p-type SCL, and the estimated hole concentration of 2.0 × 10{sup 10} cm{sup −2} agrees well with the XPS results. The estimated SCL hole concentrations were much smaller than the excess charge density in the F{sub 4}-TCNQ layer, of the order of 10{sup 13} cm{sup −2}, suggesting that most of charges were localized as the oxidation states at the SiO{sub 2}-Si(111) interface region. The present quantitative methods ensure precise determination of the doping concentration near the surface region.

• OSTI ID: 22273595
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 14 Vol. 115; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHARGE DENSITY
CONCENTRATION RATIO
CRYSTAL STRUCTURE
DEPLETION LAYER
ELECTRIC CONDUCTIVITY
ELECTRON SPECTRA
HETEROCYCLIC COMPOUNDS
HOLES
MOLECULES
NITRILES
SILICON
SILICON OXIDES
SURFACES
VALENCE
X-RAY PHOTOELECTRON SPECTROSCOPY