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 are ≲2.4 eV. At lower energies, band tailing with an Urbach focus is found. , the width of the tail, is quantitatively explained in terms of the annealing temperature . Increasing (<700 K) reduces the hydrogen content, lowers , and appears to harden the films. is determined to be a linear function of . Additional analysis was performed in terms of a divergence temperature, ; the results of this analysis are comparable to those observed in a-Si:H.
- Received 17 April 1989
DOI:https://doi.org/10.1103/PhysRevB.40.5956
©1989 American Physical Society