Investigation of Gate-controled Electron-Emittor

在MOS或MIM结构电容器的栅电极加正偏压时，发现了栅电极边缘的电子发射现象。通过观察阳极上形成的荧光屏上的光点，证实了电子发射的证据。阳极置于样品电容器附近，收集发射的电子。MOS型实验装置是在p-Si衬底，其上形成SiO2层和金属电极。大多数MIM型实验器件由薄CeO 2膜作为绝缘层夹在下电极和上栅电极之间构成。这些金属电极的材料可以从Al、Au、Cr和Ti中的几种组合中选择。电子从沿着栅极边缘的几个非常小的点发射。特别是，当栅电极蒸发时，在栅电极上产生小孔，可以有效地获得发射电流。发射电流通常伴随着大的波动和不稳定性，但在某些情况下，尽管电子是从10微米量级的非常小的点发射的，但仍显示出非常大的电流量级。只有当以下3个过程都运行良好时，才认为发生排放。(1)电子从Si衬底或下电极注入到氧化物或绝缘体层。(2)氧化层或绝缘层中的电子输运。(3)电子从氧化层或绝缘层表面发射，其中超热电子的注入是在很高的电场强度下最重要的过程，它被认为是遵循Fowlar-Nordheim隧穿效应的。电子注入源自氧化物与半导体或绝缘体与金属电极之间的界面处的晶格缺陷或杂质原子的某些位置，在该界面处势垒变薄并降低。

An electron-emission phenomenons from edges of gate-electrodes of MOS or MIM structure capacitors is found when the gate-electrodes are biased by positive voltages.The evidence of the-electron-emission is confirmed by observing light spots of a fluorescent screen formed on an anode which is placed adjacent to the sample capacitor to collect the emitted electron.The MOS-type experimental device is constructed on a p-Si substrate upon which a SiO2 layer and a metal electrode are formed. Most of MIM-type experimental devices are made up of a thin CeO2 film as an insulator layer sandwiched by a lower-electrode and an upper gate-electrode. Materials of these metal electrodes are chosen in several combinations from Al, Au, Cr and Ti.The electrons are emitted from a few very small spots along the edges of the gate-electrode. Especially, the emission current can be obtained efficiently from small holes which happen to generate on the gate-electrode when the gateelectrode is evaporated.The emitted current-is generally accompanied with large fluctuation and instability but in some cases shows very large current of the order of mirriampere in spite of the electrons are emitted from a very small spot of the order of 10 micrometers.The electron-emission is considered to occur only when following 3 processes are all well-operated. (1) Electron injection from the Si-substrate or the lower-electrode to the oxide or insulator layer. (2) Electron transportation in the oxide or insulator layer. (3) Electron emission from the surface of the oxide or insulator layer.Above all, the injection of hot electrons which is considered to obey FowlarNordheim tunneling effect is most important process under the very high electric field strength. The electron injection originates from some sites of lattice imperfections or impurity atoms at the interface between the oxide and the semiconductor or the insulator and the metal electrode where the potential barriers are thinned and lowered.