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本文研究了用ZnS多晶薄膜作绝缘层时制备的ZnSe MIS二极管,在正向电压激发下的蓝色电致发光的空间分布,在光学显微镜下观察到电致发光呈稀疏的点状分布。为了了解发光点的起因,用扫描电镜观测了二极管的二次电子像(SEI),束感生电流像(EBICI)和吸收电流像(AEI)。一个重要的发现是二极管的电致发光点(ELS)和EBICI有相当好的对应关系。文中指出了发光点的存在与绝缘层(Ⅰ)的引入有关。绝缘层一半导体(I-S)界面较大的能带失配和较差的结合,从而产生较多的无辐射复合中心,是产生稀疏发光点可能的原因。文中根据对发光点起因的分析,提出用ZnSe多晶薄膜取代ZnS多晶薄膜作绝缘层来铡备ZnSe MIS二极管。当用显微镜观察时,电致发光点呈密集分布,而用肉眼观察时是均匀的蓝色发光。文中还指出了进一步改进电致发光空间分布的可能途径。
In this paper, the ZnSe MIS diode prepared by using ZnS polycrystalline thin film as an insulating layer is studied. The blue electroluminescence under the excitation of forward voltage is spatially distributed, and the spot distribution of electroluminescence is observed sparsely under the light microscope. In order to understand the origin of the light-emitting point, the secondary electron image (SEI), beam induced current (EBICI) and absorption current (AEI) of the diode were observed by SEM. An important finding is that there is a good correspondence between the diode electroluminescent spot (ELS) and EBICI. The article pointed out that the existence of light-emitting point and the insulation layer (Ⅰ) on the introduction. A larger mismatch and poorer bond at the I-S interface, resulting in more radiation-free recombination centers, is a possible cause of sparse emission points. According to the analysis of the origin of the light-emitting point, ZnSe polycrystalline thin film is proposed to replace the ZnS polycrystalline thin film as the insulating layer to prepare the ZnSe MIS diode. When observed with a microscope, the electroluminescent spots are densely distributed and are uniformly blue when viewed with the naked eye. The article also pointed out possible ways to further improve the spatial distribution of electroluminescence.