Texture control of ZnO films by inductively coupled plasma assisted chemical vapor deposition

ZnO films were grown on Si (100) and quartz substrates by inductively coupled plasma-assisted chemical vapor deposition using diethylzinc, O2, and Ar. ZnO films with the (002) preferred orientation (PO) were formed at substrate temperatures > 250 °C regardless of any other changes made to process variables, since the (002) plane has the lowest formation energy with the highest number of unsaturated Zn–ZnO or O–ZnO bonds. At temperatures < 250 °C, the a-axis plane PO such as (100), (110), and (101) as well as the c-axis (002) plane PO were able to form by varying the temperature, plasma power, and deposition rate. The a-axis PO was formed when the radio frequency power was high enough to produce a crystalline ZnO film but was insufficient to form a (002) PO. The a-axis PO was also formed at higher deposition rates ≥ 20 nm/min when the radio frequency power was high enough to produce crystalline ZnO film. Since the (002) plane grew slowly, the grain exposing (002) plane was overgrown by the grains of the a-axis plane at higher deposition rates.