Mg含量对Mgx Zn1-x O：Ga薄膜电学性质的影响

摘要

通过金属有机物化学气相沉积法制备了不同Mg组分的MgxZn1-xO：Ga(x=0,0.03,0.14)薄膜。透射谱中Mgx Zn1-x O：Ga薄膜的光学带隙随x增大而出现的蓝移证实了Mg在ZnO晶格中的替位掺入。薄膜上金叉指电极间的变温I-V曲线显示,在同等温度下,Ga掺杂Mgx Zn1-x O薄膜的电阻率随着x值的增大而逐渐升高。这是由于Mg组分增大使材料的导带底显著上升,Ga的施主能级深度增大,导致n型载流子浓度降低。根据I-V曲线计算了270 K温度下MgxZn1-xO：Ga薄膜的浅能级施主深度。与x=0,0.03,0.14对应的施主能级深度分别为45.3,58.5,65 meV,说明随着薄膜Mg含量的升高,Ga的施主能级深度有增加的趋势。%MgxZn1-xO:Ga (x=0, 0. 03, 0. 14) films were prepared by metal organic chemical va-por deposition method. The transmission spectra of MgxZn1-xO:Ga films were measured. The optical band gap shows blue shifting on the transmission spectra with the increase of letter x. 12 pairs of in-terdigital electrodes were prepared on all MgxZn1-xO:Ga films. I-V curves of MgxZn1-xO:Ga films were measured at different temperature, and the temperature resistance curves of MgxZn1-x O: Ga films were obtained under certain voltage. The normalized R-T curve shows that the resistance of MgxZn1-xO:Ga films increases with the increasing of x at the same temperature. It is attributed to that the width of bandgap expands with the concentration of Mg ions, which leads to reduction of car-rier concentration. The ionization energy for shallow donor impurities in the MgxZn1-xO:Ga lattice was calculated. When the mole fraction of Mg is 0, 3% and 14%, the ionization energy for shallow impurity is 45. 3, 58. 5 and 65 meV, respectively. The data show that the ionization energy for Ga donor obviously increases with the increasing of Mg concentration .