Study On Field Emission Cathode Based On Nanostructured Surface Field Enhancement

Micro-vacuum electronics is the use of semiconductor processing technology to reduce the structure and size of vacuum devices to the micron and nanometer scale.It combines the advantages of solid-state devices and vacuum devices,with high frequency,low operating voltage,integrability,and miniaturization.When the electron ballistic transport distance of micro-vacuum devices is reduced to a distance comparable to the average free range of electrons in the atmosphere,micro-vacuum electronic devices reduce the requirement for vacuum packaging and can even directly realize the function of vacuum devices in the atmosphere,which greatly explores the application scope of vacuum devices.Local surface excitations confine the optical field and energy to a structure smaller than one wavelength size,which has a strong local field enhancement effect and continuously enhances the interaction between the optical field and the structure.To this end,this paper investigates a nano-surface field-enhanced structure that can work in the atmosphere,combining local surface equipartition excitations with field emission to continuously enhance the local electric field and improve its field emission performance.The experimental results show that the field emission performance of the device is stable and reproducible,with frequency-selective characteristics,and produces a strong response for lasers with power in the n W range.The main contents of this article include:（1）Local surface field enhanced structural simulation design.Using CST simulation software,two types of vertical nano-channel array devices are designed.The field emission characteristics,near-infrared absorption enhancement characteristics,and the influence of electromagnetic wave irradiation at the maximum absorption peak on the field emission performance of the two structures were studied respectively.（2）Preparation and characterization of periodic nanosurface field-enhanced structures.The device is processed and prepared according to the simulation results,the preparation process of the device is elaborated and the completed sample is characterized and analyzed.（3）Preparation and experimental testing studies of nano surface field-enhanced structures.Perform DC field emission test and NIR irradiation field emission test on the device.The DC field emission performance test results show that the device has good field emission performance with high repeatability and has the emission performance under vacuum conditions in the atmosphere.The number of arrays increases the field emission performance,and the addition of the tip structure increases the emission current.The experimental results demonstrate that the device has frequency selectivity under near-infrared irradiation,and its field emission performance is improved for low-power signals.In the experiment,the lowest optical power is 1.89 n W and the lowest optical power density was 9.43*10^-4 W/cm².The effect of power and bias on the emitting current was analyzed in subsequent shading-adding experiments.The frequency-selective characteristics of the device and its good response to small signals have been confirmed in the experiments,and it is expected to be applied to near-infrared photoelectric detection.