Nickel doping of boron–carbon alloy films and corresponding Fermi level shifts

Authors

Seong-Don Hwang, University of Nebraska-Lincoln
N. Remmes, University of Nebraska-Lincoln
Peter A. Dowben, University of Nebraska-LincolnFollow
D.N. McIlroy, University of Idaho

Date of this Version

May 1997

Comments

Published in the Journal of Vacuum Science and Technology A 15(3), May/Jun 1997. Copyright © 1997 American Vacuum Society. Used by permission. For free online abstracts, see http://www.avs.org/literature.jvst.b.aspx

Abstract

We have grown nickel doped boron–carbon alloy films by the technique of plasma enhanced chemical vapor deposition. The source gas closo-1,2-dicarbadodecaborane (orthocarborane) was used to grow the boron–carbon alloy, while nickelocene [Ni(C₅H₅)₂] was used as the dopant source for nickel. With sufficient levels of Ni doping, diodes with characteristic tunnel diode behavior can be fabricated. The doping of nickel transformed a B₅C p-type material, relative to lightly doped n-type silicon, to a strongly n-type material. In order to gain insight into the shift of the Fermi level of the Ni-doped material, we have examined the changes in the electronic structure of sodium doped films of the precursor molecule orthocarborane which has an icosahedral structure similar to that of boron–carbon materials. The establishment of unoccupied states at the Fermi level with Na doping of the orthocarborane films is consistent with the transformation of the p-type B₅C to an n-type material with Ni doping.