Cu掺杂浓度对ZnO/PS纳米复合体系光学性能的影响

Effect of Cu doping on the optical properties of ZnO/PS nanocomposite systems

用电化学阳极氧化法腐蚀p型(100)的单晶硅片制成多孔硅(PS)衬底,然后采用射频反应磁控溅射技术在PS衬底上沉积了不同Cu掺杂浓度的ZnO薄膜.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外分光光度计和荧光分光光度计研究了不同Cu掺杂浓度对薄膜结构和光学性能的影响.XRD结果显示:所有样品都呈现出较强的(002)衍射峰,有很好的c轴择优取向;SEM形貌显示:ZnO晶粒覆盖了PS的孔洞,薄膜表面平整,晶界较明显;透射吸收谱显示:ZnO薄膜有较高的平均透射率,并随着Cu掺杂量的增加而降低,光学带隙值由3.22eV减小到3.15eV;样品的光致发光谱显示:ZnO/PS纳米复合体系在可见光区(380—750nm)形成了较宽的发光带,并且掺杂浓度对发光强度有显著的影响.ZnO的蓝光、绿光与PS的红橙光叠加,呈现出了较宽的白光发射.

ZnO films doped with different Cu concentration are prepared on porous silicon（PS） substrate by RF magnetron sputtering technique.PS samples are formed by electrochemical anodization on p-type（100） silicon wafer.The influence of different Cu doping concentration on the microstructure and optical properties of ZnO films are investigated by using X-ray diffraction（XRD）,scanning electron microscope（SEM） and photoluminescence.The results of XRD show that all the samples have a strong diffraction peak and high preferential orientation in the（002） crystallographic direction.From the SEM images,it can be found that the ZnO nanoparticles sputtered from the target cover the porous silicon surface,exhibiting a smooth surface and obvious grain boundaries.The transmission spectrum show that all these films have a high transmittance ratio in the visible region and the transmittance ratio decreases with the incorporation Cu ion concentration increasing.The optical band edge decreases from 3.22 eV to 3.15 eV.The photoluminescence spectrum show that ZnO/PS nanocomposite formes a broad PL band including the blue,green emissions and red-orange emission.With the increase of Cu doping concentration,the intensity of the samples＇ emission peak decreases sharply.The blue and green emission from ZnO and red emission from PS are combined,thereby producing broad white light.