衬底温度对Zn0.85 Mg0.13 Al0.020薄膜结构和发光特性的影响

采用射频磁控溅射方法,在Si(111)基片上制备出Zn0.85Mg0.13Al0.02O薄膜。X射线衍射(XRD)证实Zn0.85Mg0.13Al0.02O薄膜为单相六角钎锌矿结构,衬底温度从室温升高到500℃,薄膜沿c轴择优生长。原子力显微镜(AFM)测量显示薄膜表面粗糙度随衬底温度的升高由9.32nm增加到19.94nm。荧光光谱仪(PL)测量显示薄膜在397nm附近有强的紫光发射,在486nm处有弱的蓝光峰,随衬底温度的升高紫峰强度提高15倍。在可见光范围内,薄膜平均透过率随衬底温度的升高由75%增加到95%,薄膜光学带隙分别为3.18,3.18和3.19eV。分析表明紫峰来自于自由激子复合,蓝峰由俘获在施主能级Zn填隙中的电子与俘获在受主能级Zn空位中的空穴复合而产生发光。

Influences of substrate temperature on the structure and photoluminescence of Zn0.85Mg0.13Al0.02o thin films

Zn_(0.85)Mg_(0.13)Al_(0.020) thin films have been deposited on Si (111) substrates at temperatures ran-ging from room temperature to 700 ℃. by radio frequency magnetron sputtering. The influence of growth temperatures on the micorstructure, morphology and photoluminescence properties of thin films was inves-tigated by X - ray diffraction ( XRD), atomic force microscopy ( AFM ) and photoluminescence ( PL) measurement at temperature room. The results indicate that the thin films have hexagonal wurtzite single phase structure, strong violet photoluminescence peaks(397nm) and weak blue photoluminescence peaks (486nm). We assign that the violet peaks derived from free excition radiation recombination, blue photo-luminescence peaks originated from Zn vacancy and Zn interstitial defects. All films show 75% -95% optical transmission in the visible range. With increasing growth temperature the intensities of the XRD (002) peaks increase, thin films have a prefered orientation with the c axis perpendicular to the sub-strate, surface roughness, intensities of violet photoluminescence peaks and optical transmission also in-crease. The optical band gap energies determinded from the obtained transmittance spectras are 3. 18,3. 18,and 3. 19eV. It demonstrates that high quality Zn_(0.85)Mg_(0.13)Al_(0.020) thin films deposited by RF magne-tron sputtering can be obtained by properly controlling the substrat temperature.