Fabrication of ZnO Films Alloyed with LiGaO₂ by RF-Magnetron Sputtering and Their Optical Property

The alloyed thin films of ZnO with LiGaO 2 were fabricated by an rf-magnetron sputtering technique using the target materials with various LiGaO 2 concentrations. After optimizing the deposition conditions, such as sputtering atmosphere, applied rf-power and pressure, we successfully obtained almost stoichiometric x (LiGaO 2 ) 1/2 ·(1- x )ZnO alloyed films. All the obtained films were identified as the simple wurtzite phase. An immiscible region of 0.5 < x < 0.85 was concluded on the basis of a clear discontinuity in the variation of the lattice parameters and energy band gap as a function of the alloying level. For the lower LiGaO 2 concentration films, the energy band gap increased with that increasing alloying level and it was widened up to 3.97 eV for x = 0.49, although a significant band gap bowing was observed. The broad absorption in the visible to near-infrared region attributable to the conduction electrons was clearly detected in the transmission spectra of the as-deposited films with 0 ≤ x ≤0.5.