Relation between solubility of silicon in High-k oxides and the effect of fermi level pinning

N. Umezawa, K. Shiraishi, K. Kakushima, H. Iwai, K. Ohmori, K. Yamada, T. Chikyow

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

HfO2-based oxide is a promising gate insulator for the next generation of the field effect transistors. Yet it is accompanied by a problematic effect, that is, the Fermi level of a metal electrode deposited on HfO2 is pinned at a certain position regardless of the type of the metal. On the other hand, this effect, the so-called Fremi level pinning, does not occur in a metal/La2/O3/Si gate stack. This is puzzling because both oxides have similar band gaps and dielectric constants. We suggest that the high solubility of Si in La2O3, and thereby the formation of a silicate layer LaxSiyO z between La2O3 and the Si substrate plays important role in the suppression of electron transfers from La 2O3 to the metal electrode: The charge neutrality is satisfied at the ionic/ionic interface La2O3/La xSiyOz, and thus there is no need to exchange electrons with outside. At the ionic/covalent interface HfO2/SiO 2, however, the charge neutrality is insufficient and electrons are readily transferred into the metal electrode causing the Fermi level pinning.

Original languageEnglish
Title of host publicationECS Transactions - Dielectrics for Nanosystems 3
Subtitle of host publicationMaterials Science, Processing, Reliability, and Manufacturing
Pages15-20
Number of pages6
Edition2
DOIs
Publication statusPublished - 2008
Event3rd International Symposium on Dielectrics for Nanosystems: Materials Science, Processing, Reliability and Manufacturing - 213th ECS Meeting - Phoenix, AZ, United States
Duration: 2008 May 182008 May 22

Publication series

NameECS Transactions
Number2
Volume13
ISSN (Print)1938-5862
ISSN (Electronic)1938-6737

Other

Other3rd International Symposium on Dielectrics for Nanosystems: Materials Science, Processing, Reliability and Manufacturing - 213th ECS Meeting
CountryUnited States
CityPhoenix, AZ
Period08/5/1808/5/22

ASJC Scopus subject areas

  • Engineering(all)

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