Study On The Preparation Of MIM Cold Cathode And Its Characteristics

The Metal-Insulator-Metal(MIM)type cathode is a kind of internal field emission cathode,which has the advantages of small volume,no preheating,low noise,low working voltage and low vacuum requirement.The overall thickness of the cathode structure is generally no more than 1 micron,is a nano-thin film process,in the thin film electronic devices and low power vacuum devices have great application prospects and research value.In this paper,starting from the characterization of the film,the MIM cathode was prepared by different process in the laboratory,the emission performance of the cathode was tested and the factors affecting the emission performance were analyzed.The main contents of this paper are as follows:(1)Al-Al2O3-Au cathode structure was used as the research object,the insulating layer Al2O3 was prepared by reactive sputtering and anodic oxidation,the process parameters were optimized.After several tests,the Au film was deposited with the power of 15 W for 20 s in DC sputtering as the top electrode has the best electron emission capability.At a pressure of 1 Pa,Ar:O2 in proportion of 100sccm:25sccm by reactive sputtering for 1 hour at a power of 100 W,the prepared Al2O3 is used as an insulating layer with a compressive strength of about 18 V.The insulating layer prepared by anodic oxidation at the voltage of 150 V in ethylene glycol solution of 5% by weight of ammonium succinate used for 12 hours to have a compressive strength of about 27 V,used as the insulating layer maximizes the emission current of 9mm2 single array to 116.5uA and the current density is 1.29 mA /cm2.(2)The PMMA(polymethylmethacrylate)method was used to replace the graphene film instead of the top electrode Au.It was found that the sample of the transferred 4-layer graphene film had the best emission performance,but not as good as Au for the top electrode,that may be with the growth of graphene film quality,transfer quality,substrate roughness and so on.(3)The application of large-area MIM cathode array was studied.The 2×2 array,3×3 array and 14×11 cathode array were tested by the phosphor screen.From the screen image,Multi-array cathode emission is uneven.As the cathode area gradually increases,the emission current density is greatly reduced,the maximum current density of the 14×11 array cathode with a total area of 1.54cm2 is 180.7uA /cm2.By optimizing the preparation process and equipment can improve the cathode emission performance,so that it has practical application prospect for low power and low noise electron source.