【作者】 李丹；

【导师】 沈鸿烈；

【作者基本信息】 南京航空航天大学 ， 材料学， 2008， 硕士

【摘要】 以硝酸锌和硝酸钾混合溶液为电解液,采用两电极体系在FTO基片和p-Si(100)衬底上制备了c-轴取向的ZnO薄膜。通过改变电沉积过程的各种参数,获得了具有不同形态和性能的ZnO纳米晶薄膜。研究发现,改变沉积电压和外加超声振动能够对薄膜的形貌和结构产生强烈的影响;不同沉积电压下的薄膜生长方式不同,在较低电压下,薄膜生长方式为岛状生长;随着沉积电压的升高,薄膜的生长方式由岛状变为岛状-层状相结合的方式生长;当沉积电压达到2.8V以后,薄膜按照层状方式生长。本文用X射线衍射、扫描电子显微镜、紫外-可见和紫外-荧光分光光度计分析了薄膜的相结构,晶粒尺寸、光学性能与发光特性。发现薄膜的(002)衍射峰随着沉积电压的增加而显著增强;从扫描电镜照片可以看出,薄膜中晶粒为典型的六方柱状结构,不同样品的晶粒尺寸介于100~400nm之间。由于晶粒度大小不同,纳米晶薄膜的光学禁带宽度介于3.32~3.34eV。随着沉积电压的升高和沉积时间的延长,薄膜晶体颗粒逐渐长大,光学透过率降低。若在沉积过程中引入超声波,由于受到超声振动的抑制,薄膜晶粒的尺寸下降。若对衬底进行选择性腐蚀,使薄膜在生长初期有选择地成核,则可以制备纳米花状的ZnO纳米晶薄膜,其荧光受激发光有蓝移现象。在对ZnO/Si异质结施加电压时,异质结呈现明显PN结特性;在对ZnO/Si异质结加以光照时,异质结呈现了显著的光生电流特性。更多还原

【Abstract】 A two-electrode system was employed to fabricate c-axis oriented ZnO films on a FTO wafer and p-Si(100) substrate in a mixed Zn(NO3)2/KNO3 aqueous electrolyte. We obtained ZnO nano-crystaline films with different morphology and characteristics by adjusting the parameters in the electrodeposition process. It was discovered the morphology and structure were strongly affected by adjusting deposition voltage and applying ultrasonic wave.The film growth mode was different at different voltage, which is island growth at lower voltage and layer growth at higher voltage. With the increase of voltage, the growth mode would undergo a gradual transition from island mode to island-layer combined mode, and then to layer mode last if voltage was higher than 2.8V. In this paper, X-ray diffraction, scanning electron microscopy, UV-VIS and UV-FLU spectroscopy were employed to analyze the phase structure, surface morphology, optical absorption and stimulated luminescence properties, respectively.It was found that the (002) peak intensity of XRD patterns increased apparently with the increase of deposition voltage. The grain shapes were typically hexagonal in different samples with the grain size between 100~400 nm. The optical band gap of nano-crystalline films is between 3.32~3.34eV, due to different grain sizes. The grain sizes of film were growing up and the transmittance with the increasing of deposition voltage and time. If applied ultrasonic wave to the deposition process, the grain size of films decreased, because the inhibitory effect of ultrasonic vibration to the crystal overgrowth. Film growth would selectively nucleate at the initial stage if the substrates were selectively corroded. As a result, we can fabricate flower-like nano-crystalline film. The stimulated luminescence peak of flower-like nano-crystalline film would blue shift. The ZnO/Si heterojunction showed apparent PN junction properties under bias voltage. Under light illumination, the n-ZnO/p-Si diode presented a remarkable photocurrent effect.更多还原