氮掺杂p型Mg_xZn_(1-x)O薄膜的制备及其表征

Preparation and Characterization of Nitrogen-doped P-type Mg_xZn_(1-x)O Film

采用不同氮分压(RN2)的氩气和氮气混和气体溅射Mg0.18Zn0.82O合金靶材,在石英衬底上生长了MgxZn1-xO(MgZnO)合金薄膜,研究了氮分压对薄膜组分、结构和光学、电学性质.结果表明:薄膜中的Mg含量(x)随着RN2的增加呈线性增加,导致其结构和光学带隙(Eg)随氮分压变化.Mg含量随氮分压的变化归因于:当氮分压增加时,与N反应形成NO2的O原子数目增加,导致与Mg、Zn反应的O原子数目减少.而Mg比Zn优先与剩下的O原子结合形成MgO,导致只有部分Zn能够跟O结合形成ZnO.未反应的Zn将以原子的形式沉积到衬底上继而因高的衬底温度发生二次蒸发离开衬底,导致薄膜中Zn含量减小,即Mg含量增大.当对由氮分压不为零制备的高阻MgZnO薄膜进行真空退火后,薄膜呈p型导电,说明这种p型导电与氮掺杂有关.本文讨论了Vegard定理用于估算MgZnO中Mg含量的正确表达式.

MgxZn1-xO （MgZnO） films were grown on quartz substrate by sputtering Mg0.18Zn0.82O alloy target using mixture of nitrogen and argon gases with various nitrogen partial pressure ratios （RN2）. The Mg content （x） in the MgZnO film increases linearly with increasing RN2, resulting in changes of structure and optical bandgap （Eg） of the MgZnO with the RN2. The changes of the Mg concentration in the MgZnO with RN2 are mainly attributed to the loss of the O and Zn atoms induced by reaction between the N and O as well as high substrate temperature. The high resistant as-grown MgZnO film prepared by using the mixture gas with RN2 〉 0 is transformed into p-type conductivity after annealed under vacuum, implying that the p-type conductivity is related to nitrogen doping. We also discussed reasonable expression of Vegard law used to evaluate the Mg content.