Semiconducting hydrogenated carbon-nitrogen alloys with low defect densities

Low paramagnetic defect density hydrogenated amorphous carbon (a-C:H) films grown by radio frequency driven plasma enhanced chemical vapour deposition (rf-PECVD) system an characterised using ultraviolet/visible spectroscopy and Rutherford backscattering spectroscopy (RBS). The changes in the optica l band gap, Urbach tail width, and Tauc B-1 parameter as a function of nitr ogen flow rate and ex situ annealing from 100 to 400 degrees C for 300 s ar e examined. Particular attention is paid to changes in the film structure a fter annealing at 100 degrees C, since an increase in the E-04 optical band gap is observed as a function of nitrogen flow. This increase is shown to be a result of the restructuring of the chemical bonds present, despite the re being no change in the refractive index of the films, which suggests a d ecrease in the defect band tails of the films. (C) 2000 Elsevier Science S. A. All rights reserved.