Optical-absorption edge and disorder effects in hydrogenated amorphous diamondlike carbon films

Authors

T. Datta, University of South Carolina, Columbia, South Carolina
John A. Woollam, University of Nebraska-LincolnFollow
W. Notohamiprodjo, University of Nebraska-Lincoln

Document Type

Article

Date of this Version

4-1-1989

Comments

Published in Published in Physical Review B 40:9 (1989), 5956 - 5960. Copyright ©1989 The American Physical Society. Used by permission. URL: http://link.aps.org/abstract/PRB/v40/p5956

Abstract

Optical absorption (~1–5 eV) in rf-deposited hydrogenated (20–40 at. %) amorphous “diamondlike” carbon films has been studied as a function of heat treatment. For E >~ 2.5 eV a Tauc behavior is exhibited. Optical band gaps E_g are E₀, the width of the tail, is quantitatively explained in terms of the annealing temperature T_H. Increasing T_H (<700 >K) reduces the hydrogen content, lowers E_g, and appears to harden the films. E_g is determined to be a linear function of E₀. Additional analysis was performed in terms of a divergence temperature, T₀; the results of this analysis are comparable to those observed in a-Si:H.