Synthesis and characterization of zinc-doped amorphous carbon films by plasma-assisted organometallic chemical vapor deposition

Zinc (Zn)-doped hydrogenated amorphous carbon (a-C:H) films have been fabricated from zinc acetylacetonate by organometallic chemical vapor deposition (CVD). Zn concentration was controlled by a heated flow controller. Deposited films were Zn-doped hydrogenated oxygenated amorphous carbon films because they consisted of carbon, hydrogen, zinc, and oxide. The maximum concentration ratio of zinc to carbon (Zn/C) was as large as 0.069. Depletion of the film resistivity R was found when Zn concentration C(Zn) increased. Activation energy derived from the relationship between R and CZn changed from 38.2 to 7.1 meV when Zn/C ratio increased from 0.008 to 0.069. Photovoltaic characteristics of a Zn-doped a-C:O:H/n-Si cell also depend on the Zn concentration. Above the ratio of Zn/C = 0.019 in the Zn-doped a-C:O:H layer, the polarity relationship of n-Si was inversely proportional against the polarity of the film deposited at the lowest Zn concentration of Zn/C = 0.008. The open-circuit voltage and short-circuit current of a device consisting of n-Si and Zn-doped a-C:O:H films were 93 mV and 0.16 mu A/W when Zn/C was 0.019, respectively. These results show that organometallic CVD using a solid organometallic complex is a promising method of fabricating metal-doped a-C:H films for electrical applications.