Effects of Hydrogen on the Optical and Electrical Characteristics of the Sputter‐Deposited Al 2 O 3 ‐Doped ZnO Thin Films

In this study, AZO thin films were deposited on glass by using a 98 mol% ZnO + 1 mol% Al 2 O 3 (AZO, Zn : Al = 98 : 2) ceramic target and a r.f. magnetron sputtering system. At first, the effects of different H 2 flow rates (H 2 /(H 2 + Ar) = 0% ~ 9.09%, abbreviated as H 2 ‐deposited AZO thin films, deposition temperature was 200°C) added during the deposition process on the physical and electrical properties of AZO thin films were investigated. The optical transmittance at 400 nm ~ 700 nm is more than 80% for all AZO thin films regardless of H 2 flow rate and the transparency ratio decreased as the H 2 flow rate increased. The Burstein‐Moss shift effect was used to prove that the defects of AZO thin films decreased with increasing H 2 flow rate. Also, the 2% H 2 ‐deposited AZO thin films were also treated by the H 2 plasma at room temperature for 60 min (plasma‐treated AZO thin films). The value variations in the optical band gap ( E g ) values of the H 2 ‐deposited and plasma‐treated AZO thin films were evaluated from the plots of ( α h ν ) 2 = c ( h ν − E g ), and the E g values increased with increasing H 2 flow rate. The E g values also increased as the H 2 ‐plasma process was used to treat on the H 2 ‐deposited Al 2 O 3 ‐doped ZnO (AZO) thin films.