Effects of group III dopants on the structural and optical properties of sol-gel derived zno thin films

Abstract

In this research, the effect of group III dopants on the structural and optical properties of zinc oxide (ZnO) thin films was investigated. Undoped, Al-, Ga-, and In-doped ZnO thin films at a constant 3 at.% doping content were fabricated by the simple route of a sol-gel spin coating process followed by an annealing technique in an ambient pressure at 500°C. Zinc acetate dihydrate ( Zn(CH 3 COO) 2 · 2 H 2 O), aluminum nitrate nonahydrate (Al(NO 3 ) 3 ·9H 2 O), gallium (III) nitrate hydrate (Ga(NO 3 ) 3 ·xH 2 O), and indium (III) acetate (In(CH 3 COO) 3 ) were used as the starting materials for Zn, Al, Ga, and In sources, respectively. The structural properties of undoped and group III-doped ZnO thin films agreed with the hexagonal wurtzite crystal structure. Moreover, incorporation of group III dopants into the ZnO lattice was able to decrease the grain size and deteriorate the crystallinity of the ZnO. The transmittance phenomena in the visible region of all thin films was shown to be higher than 92%. Furthermore, the optical band gap of ZnO doping with group III dopants is higher than for purified ZnO. In the same way, the morphology of ZnO has a sharp distinction with various types of group III dopants.