氧化锌薄膜的电化学沉积法制备及受激发射研究

采用一种简单的电化学沉积法，在三电极化学池中，以单一的硝酸锌水溶液作为电沉积液，制备了高光学质量的半导体ZnO薄膜。透射光谱测量表明其光学带隙为3．35eV，400～2000nm波段的光学透过率大于80％。X射线衍射(XRD)和原子力显微镜(AFM)研究表明，ZnO薄膜为纤锌矿结构的无序多晶颗粒膜，微晶尺寸小于250nm。当用355nm的皮秒脉冲激光作为抽运源垂直入射薄膜表面时，可以检测到400nm附近的近紫外受激发射光，其强度随入射强度呈超线性增长关系，阈值在196．8kW／cm^2处，并且激光发射是多模的和各个方向的，还与被激发的面积有关，表现为随机激光发射机制。

Electrochemical Deposition and Stimulated Emission of Zinc Oxide Thin Films

Wide bandgap semiconductor zinc oxide thin films have been prepared by an electrochemical deposition performed in a chemical cell with three-electrodes, using an aqueous solution of Zn(NO_3)_2 as electrodeposition solution. The obtained ZnO thin films have optical bandgap of 3.35 eV and optical transmittance larger than 80% in the range of 400～2000 nm determined from their optical transmission spectra. XRD pattern indicates hexagonal wurtzite structure without c axis orientation for the ZnO thin films. AFM studies show a dense, irregular polycrystalline film structure with grain size below 250 nm. Stimulated emission occurs at a close ultraviolte wavelength of 403.9 nm under 355 nm optical pumping. When the excitation intensity exceeds a threshold (about 196.8 kW/cm2), very narrow emission peak (FWHM=0.5 nm) emerges and its intensity increases superlinearly with increasing the pump power. The stimulated eimission light is multimode laser relative to incident area and can be observed in all directions, showing a random laser emission due to the formation of a closed-loop path for scattered light in the ZnO thin film.