Plasma processes and film growth of expanding thermal plasma deposited textured zinc oxide

Plasma processes and film growth of textured zinc oxide deposited from oxygen and diethyl zinc utilizing expanding thermal argon plasma created by a cascaded are is discussed. In all conditions explored, an excess of argon ions and low temperature electrons is available, which represent the chemistry taking place. The plasma induced decomposition mechanism involves charge exchange with argon ions, and consecutive dissociative recombination with electrons emanating from the cascaded arc plasma source. The presence of reactive atomic species, specifically Zn* and O*, is confirmed with the help of optical emission spectroscopic measurements. The absence of residual carbon in the films suggests a mechanism involving the dissociation of the Zn-C bonds in the plasma instead of at the surface. Film growth appears to proceed by the adsorption of particular zinc species, followed by subsequent reaction with oxygen, with the deposition rate being directly proportional to the arrival rate of the particular reactive species. It is suggested that atomic zinc adsorbs on the surface in a weakly bounded highly mobile state. Best intrinsic transparent conducting oxide quality, that is film conductivity, is obtained at the highest deposition rate.