Transparent P-type Conductive Ternary Oxide Films Prepared by Reactive Sputtering Method

在ar稀释的O_2（5 ~ 20%）气氛下，在500 ~ 700℃的原子层尺度上交替溅射Cu和Al靶材，在石英衬底上制备Cu-Al- o薄膜，然后在1050℃的氮气气氛下退火。[Cu]/[Al]比值可通过改变Cu和Al沉积时间来控制。沉积膜的组成与CuO-CuAl_2O_4-Al_2O_3体系的略富氧区相对应。500℃沉积膜为非晶相，700℃沉积膜为CuAl_2O_4相和CuO相。热退火后，膜的组成接近cu_2o_2 -CuAlO_2- al_2o_3系线，出现了明显的CuAl_2O_4 + CuAl_2O_4 + CuO相，而CuAl_2O_4 + CuO相缺失。富cu和富al退火膜分别有额外的Cu_2O相和无定形Al_2O_3相。所有退火膜均呈现p型电导率。[Cu]/[Al]【近似等于】1的退火膜的吸收边与CuAlO_2的能隙相对应。这些结果表明，在退火过程中，Cu离子由二价变为单价，从而制备出以CuAlO_2为主的透明导电薄膜。我们还尝试用功率在10 ~ 10^3 mJcm^<-2>的KrF激光照射沉积薄膜，使其非晶化为CuAlO_2的非晶化结构。然而，我们没有观察到非晶结构的变化。在功率大于约10^2 mJcm^<-2>时，观察到薄膜的激光烧蚀。

Cu-Al-O films were prepared on quarts substrates at 500〜700℃ by sputtering alternately the Cu and the Al targets on atomic-layer-scale under Ar-diluted O_2(5〜20%) gas atmosphere, and then annealed at 1050℃ under the nitrogen atmosphere. The [Cu]/[Al] ratio was controlled by changing Cu and Al deposition periods. Composition of as-deposited films corresponded to the slightly oxygen-rich region of the CuO-CuAl_2O_4-Al_2O_3 system. Films as-deposited at 500℃ had amorphous structure, while films as-deposited at 700℃ had CuAl_2O_4 and CuO phases. After thermal annealing, the film composition approached to the Cu_2O-CuAlO_2-Al_2O_3 system line, causing noticeable appearance of CuAlO_2 delafossite phase along with absences of the CuAl_2O_4 and CuO phases. Cu-rich and Al-rich annealed films had additionally Cu_2O phase and amorphous Al_2O_3 phase, respectively. All annealed films exhibited p-type conductivity. The annealed films with [Cu]/[Al]【approximately equal】1 had the absorption edge corresponding to the energy gap of CuAlO_2. These results indicate the change of Cu ion from di-valence to mono-valence through the annealing process, which results the preparation of transparent conductive films dominated by CuAlO_2. We also tried to irradiate the as-deposited films in order to crystallize the amorphous structure to CuAlO_2 delafossite structure by using a KrF laser in the power range of 10〜10^3 mJcm^<-2>. However, we observed no changes of the amorphous structure. At the power more than about 10^2 mJcm^<-2>, laser ablation of the films was observed.