Electrical properties of amorphous and epitaxial Si-rich silicide films composed of W-atom-encapsulated Si clusters

Journal Article · Sat Mar 07 00:00:00 EST 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4913859· OSTI ID:22413226

Okada, Naoya ^[1]; Uchida, Noriyuki ^[2]; Kanayama, Toshihiko ^[3]

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1. Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)
2. Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562 (Japan)
3. Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

We investigated the electrical properties and derived the energy band structures of amorphous Si-rich W silicide (a-WSi{sub n}) films and approximately 1-nm-thick crystalline WSi{sub n} epitaxial films (e-WSi{sub n}) on Si (100) substrates with composition n = 8–10, both composed of Si{sub n} clusters each of which encapsulates a W atom (WSi{sub n} clusters). The effect of annealing in the temperature range of 300–500 °C was also investigated. The Hall measurements at room temperature revealed that a-WSi{sub n} is a nearly intrinsic semiconductor, whereas e-WSi{sub n} is an n-type semiconductor with electron mobility of ∼8 cm{sup 2}/V s and high sheet electron density of ∼7 × 10{sup 12 }cm{sup −2}. According to the temperature dependence of the electrical properties, a-WSi{sub n} has a mobility gap of ∼0.1 eV and mid gap states in the region of 10{sup 19 }cm{sup −3} eV{sup −1} in an optical gap of ∼0.6 eV with considerable band tail states; e-WSi{sub n} has a donor level of ∼0.1 eV with sheet density in the region of 10{sup 12 }cm{sup −2} in a band gap of ∼0.3 eV. These semiconducting band structures are primarily attributed to the open band-gap properties of the constituting WSi{sub n} cluster. In a-WSi{sub n}, the random network of the clusters generates the band tail states, and the formation of Si dangling bonds results in the generation of mid gap states; in e-WSi{sub n}, the original cluster structure is highly distorted to accommodate the Si lattice, resulting in the formation of intrinsic defects responsible for the donor level.

• OSTI ID: 22413226
• Journal Information: Journal of Applied Physics, Vol. 117, Issue 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
APPROXIMATIONS
ELECTRICAL PROPERTIES
ELECTRON DENSITY
ELECTRON MOBILITY
ELECTRONIC STRUCTURE
ENERGY GAP
EPITAXY
EV RANGE
FILMS
HALL EFFECT
RANDOMNESS
SEMICONDUCTOR MATERIALS
SUBSTRATES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TUNGSTEN SILICIDES