高掺锌/镁铌酸锂薄膜的光电性质

室温下采用射频磁控溅射(RFMS)技术在玻璃与硅基板上分别沉积了纯铌酸锂LN薄膜、高掺锌(6%,摩尔分数,下同)LN∶ZnO薄膜和高掺镁(5%)LN∶MgO薄膜,并在575 ℃条件下退火进一步提高薄膜的结晶度。通过原子力显微镜(AFM)、X射线衍射(XRD)、紫外可见吸收(UV-Vis)和椭偏仪等测试研究了三种铌酸锂薄膜的形貌、结构和光学性质。XRD分析表明掺杂铌酸锂薄膜和纯铌酸锂薄膜具有相同的生长取向,AFM、XRD、UV-Vis测试结果表明,掺杂将增大铌酸锂薄膜的晶粒尺寸,光学带隙的红移现象与晶粒尺寸相关,且掺Mg的影响大于掺Zn。此外利用霍尔效应测试仪研究了LN、LN∶ZnO和LN∶MgO薄膜的电学性质,测试结果表明三种薄膜均为n型半导体,其中LN∶MgO薄膜电导率的变化趋势不同于LN∶ZnO和LN薄膜,且发现温度在18~50 ℃范围内,随着温度的升高,LN∶MgO薄膜的电导率变化微小,而LN∶ZnO和LN薄膜的电导率逐渐增大。

Optical and Electrical Properties of High Doping Zn/Mg LiNbO3 Films

LiNbO₃ (LN), 6% zinc-doped LiNbO₃ (LN∶ZnO) and 5% magnesia-doped LiNbO₃ (LN∶MgO) films were deposited on glass and silicon substrates at room temperature by radio frequency magnetron sputtering (RFMS) method. The deposited LN, LN∶ZnO and LN∶MgO films were annealed at 575 ℃ for improving crystallinity. The morphology, structure and optical properties of the films were investigated systematically by AFM, XRD, UV-Vis and the spectroscopic ellipsometer. XRD analysis shows that high doping Zn/Mg LN films and LN film have the same growth orientation. AFM, XRD and UV-Vis measurement results show that doping Zn/Mg will increase the grain size of LN films, and the red shift of the optical band gap is related to the grain size of the films. Moreover, the electrical properties of the deposited films were measured by Hall-effect instrument. The Hall-effect test indicates that the deposited LN, LN∶ZnO and LN∶MgO films are n-type semiconductor, and the change trend of the conductivity of LN∶MgO film is different from that of LN∶ZnO and LN films. It was found that the conductivity of LN∶MgO film is almost unchanged, LN∶ZnO and LN films gradually increases with the increase of temperature in temperature of 18 ℃ to 50 ℃.