Preparation And Photoelectric Properties Of Doped Amorphous Carbon Films

Amorphous carbon film,a long-range disorder but short-range order structure material,which combines the excellent characteristics of diamond and graphite is excellent in optics,electricity,mechanics,thermals and chemical steady state.Therefore,it is a very attractive field and has been widely applied in photoelectric sensors,protective coatings,solar cells,etc.By changing the growth conditions,we can regulate the radio of sp~2(representing the degree of graphitization)/sp~3(representing the degree of diamondization)hybridized carbon atoms and fabricate the materials with different properties.In this thesis,we have prepared amorphous carbon films on silicon substrates by RF magnetron sputtering to investigate the relations between the growth conditions and film properties.The photoelectric properties of un-doped and Co doped amorphous carbon films have been discussed.The amorphous structure of the samples was analyzed by Raman spectroscopy.The surface morphology of the samples was measured by atomic force microscope and scanning electron microscope.The results show that the difference of substrate temperature,sputtering pressure and power will influence the surface morphology,resistance value and deposition rate.In other words,the amorphous carbon can be transformed into graphite or diamond,leading a change of optical and electrical properties.This study provides a strong support to the application of amorphous carbon films.In the study of the photoelectric properties of amorphous carbon films,we found that Co dopant could influence the disorder degree and change the peak position of the optical absorption spectrum.We also found that amorphous carbon films had an instant photoelectric response and the response area can be controlled by doping.On the other hand,with the advances of science and technology,more and more people have begun to pay attention to the functionality,entertainment and convenience of devices.Flexible wearable devices have emerged at this time and developed rapidly.In this thesis,the flexible amorphous carbon is successfully fabricated.The preparation method is based on a lift-off technique in which an amorphous carbon film prepared by magnetron sputtering is peeled off and transferred onto a flexible polyethylene substrate.After transferring,amorphous carbon films exhibited a large piezoresistive effect and excellent anti-fatigue effect.It is found that the photoelectric properties of flexible amorphous carbon films could be modulated by bending and doping.Although the photoconductivity is not superior to the amorphous carbon film on the Si substrate,it still has a great application prospect for its tunable characteristics.