Optimization of pulsed laser deposited ZnO thin-film growth parameters for thin-film transistors (TFT) application

摘要

In this work we present the optimization of zinc oxide (ZnO) film properties for a thin-film transistor (TFT) application.Thin films,50 ± 10 nm,of ZnO were deposited by Pulsed Laser Deposition (PLD) under a variety of growth conditions.The oxygen pressure,laser fluence,substrate temperature and annealing conditions were varied as a part of this study.Mobility and carrier concentration were the focus of the optimization.While room-temperature ZnO growths followed by air and oxygen annealing showed improvement in the (002) phase formation with a carrier concentration in the order of 10~(17)-10~(18)/cm~3 with low mobility in the range of 0.01-0.1 cm~2/Vs,a Hall mobility of 8 cm~2/Vs and a carrier concentration of 5 × 10~(14)/cm~3 have been achieved on a relatively low temperature growth (250 ℃) of ZnO.The low carrier concentration indicates that the number of defects have been reduced by a magnitude of nearly a 1000 as compared to the room-temperature annealed growths.Also,it was very clearly seen that for the (002) oriented films of ZnO a high mobility film is achieved.