Effects of deposition temperatures and annealing conditions on the microstructural, electrical and optical properties of polycrystalline Al-doped ZnO thin films

Effects of annealing conditions and film thickness on electrical and optical properties of epitaxial Al-doped ZnO films

“…So, the optimisation of the annealing process may result in markedly improved electrical properties of doped ZnO films. Contrary to the numerous data in the literature on the annealing of polycrystalline doped ZnO films grown by different physical and chemical techniques on glass substrates, the literature contains only a few studies that present some results on the influence of the annealing on the properties of epitaxial films [11][12][13][14], moreover, the reported results are not systematic and rather contradictory.…”

“…As-deposited films contain large crystallites and exhibit a high carrier mobility (>50 cm 2 V -1 s -1 ) and carrier concentration (>10 20 cm -3 ). At such a high carrier concentration, the scattering by the ionised impurities in the bulk dominates over the scattering at grain boundaries [12,24,25]. Therefore, the carrier mobility is less sensitive to such type of annealing, and its small increase is probably caused by a partial annealing of point defects or dislocations, thus reducing the scattering at such centres.…”

“…Reversible oxygen sorption/desorption process may also occur on the grain boundaries, where adsorbed oxygen increases the potential barrier and traps electrons [1,12]. Annealing in an oxygen-rich atmosphere should increase the quantity of adsorbed oxygen and the carrier trap density at the grain boundaries, thus resulting in a significant decrease of the carrier concentration and mobility (influenced by the grain boundary scattering).…”

“…This effect may be explained by incorporation of hydrogen atoms as additional shallow donor centres in the crystalline lattice [8,20,21] or by diffusion of hydrogen into the grain boundaries [12,22,23],…”

Properties of ZnO:Ga thin films deposited by RF magnetron sputtering under various RF power

“…Fig. 5 shows the figure of merits (FOM) suggested by Haacke [16] a function of the RF power. It is defined as where T a is the average transmittance in the visible range and Rs the sheet resistance of the film.…”