Fabrication and optimization process of p-type Li: ZnO oxide semiconductor

• p-Type Li doped ZnO (Li: ZnO) thin films with various of Li-contents were fabricated.
• High carrier and low electrical resistivity are observed in 0.1–0.3 mol% Li.
• The optimum sputtering process parameters were demonstrated.

Li-doped ZnO films with various Li contents (0.1–0.8 mol%) were prepared by pulsed DC sputtering system with soft-chemical methods synthesized LixZn1 − xO1 − x/2 targets. It has been investigated that the structural and electrical properties of deposited films depended on the content of doping in target. We observed p-type conduction with low resistivity for 0.1–0.3 mol% and n-type with decreased resistivity for 0.6–0.8 mol% of Li content on the film. These varieties of electrical resistivity and conductivity are suggested as the role of domination between substitutional acceptor LiZn and compensation defects of LiZn–Lii complex along with increasing Li doping amounts on the film, i.e. LiZn for p-type and LiZn–Lii for n-type. We also investigate the role of sputtering variables, such as substrate temperature, sputtering power and Ar flow rate, to optimize our sputtering process. Finally, LixZn1 − xO1 − x/2p–n homojunction diode is demonstrated to confirm stability of the p-type conduction characteristic in our deposited Li: ZnO film.