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

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,more » 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.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)
  2. (Japan)
  3. Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562 (Japan)
  4. Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)
Publication Date:
OSTI Identifier:
22413226
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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