Preparation and Characterization of r.f. Magnetron Sputtered Porous ZnO Thin Films

Porous ZnO thin films were obtained from the ZnO target by r.f. Magnetron sputtering onto glass and intrinsic-Silicon (100) substrates at different substrate temperatures (473 K and 673 K) and at a fixed combined partial pressure 5 Pa of Ar+O 2 and at a fixed sputtering power of 50 W. The composition of the films deposited at 473 K reveals that the films were oxygen deficient. The structural study reveals that the films were highly c-axis oriented with wurtzite ZnO phase. The predominant peak is (002) with a significant shift in the peak position towards lower 2θ value. The surface morphological features reveal that the film surface is porous when deposited at lower substrate temperatures of 473 K. The average pore size is 82 nm. The evaluated optical energy gap of the films is 3.1 eV and increases to 3.14 eV when deposited at higher substrate temperature.