The Deposition of a-C:H Films by Pulsed Laser Ablation

Abstract

A new technique has been introduced to deposit amorphous hydrogenated carbon films (a-C:H) by pulsed laser deposition (PLD). Camphor, a natural source, has played a crucial role for the evolution of the film from amorphous carbon (a-C) to amorphous hydrogenated carbon (a-C:H). This has been confirmed by the presence of C-H stretching bond observed in the FTIR absorption spectra. The influence of camphor incorporation to the optical, electrical, and structural properties of the carbon film has been investigated by UV-visible spectroscopy, FTIR spectroscopy, Hall measurement, and Raman shift. As a kind of photo detectors, a solar cell with a-C:H/p-Si structure has been fabricated, its current-voltage (I-V) characteristics and spectral response are also studied. From the measurement of quantum efficiency, we find that the light sensing property of the new type of a-C:H film have been improved notably. In the short-wavelength region, the a-C:H layer contributes a maximum quantum efficiency as high as 30% despite the light loss by the surface electrode.