Preparation And Performance Research Of Electronic Field Emission Device Based On Porous Al₂O₃ Film

UV light sources can be employed in fields such as environmental protection,energy,process lighting,medicine,biology,and defense,but their limited development and widespread use is hampered by their low output efficiency when compared to mercury-containing UV radiation sources.Therefore,the fundamental scientific issue addressed by the current UV light source research is the development of new UV radiation mechanisms,luminescent materials,and devices to produce high-efficiency UV radiation technology.An efficient solution to one of the problems is the direct excitation of electrons for gas luminescence.In this study,electrochemical oxidation of Al films in oxalic acid,sulfuric acid,and phosphoric acid solutions utilizing an anodic oxidation procedure,respectively,was used to prepare metal-insulator-metal(MIM)field emission electron sources.Oxalic acid solution produced porous alumina samples with higher emission performance when 4%concentrations of sulfuric acid,oxalic acid,and phosphoric acid solutions were employed as electrolytes.Following optimization of the alumina film preparation procedure using oxalic acid solutions with concentrations of 3%,5%,and 8%and oxidation voltages of 20 V,30 V,and 40 V,the experimental results revealed that the device emission efficiency reached 0.15%when the oxidation voltage was 20 V and the device voltage was 17.5 V.The device’s electron emission current density increased to 212.2μA/cm2 at 5%oxalic acid electrolyte concentration and 30.5 V device voltage,reducing the negative resistance to the present effect and enhancing the stability of the device current peak-to-valley ratio to almost 1.Using 4%phosphoric acid solution to enlarge the holes in the porous alumina samples following electrochemical oxidation with oxalic acid resulted in an increase in the electron emission current density of the electron source from 220μA/cm2 to 550 μA/cm2.The porous alumina film was treated with a rapid heat treatment process at 300℃ under a nitrogen atmosphere,which reduced the defects in the film sample.The electron emission current density reached 1.2 mA/cm2,the electron emission efficiency was 22.2%,and the rise and fall of electron emission was less than 5.32%,which significantly improved the performance and stability of the device.When the MIM electron source’s electron emission properties were examined in nitrogen and xenon environments,it was discovered that the electron emission was not affected by air pressure between 10-2 Pa and 101 Pa.The emitted electrons excite or ionize the gas when the nitrogen gas pressure reaches 3.9 Pa and the xenon gas pressure reaches 5.0 × 102 Pa,leading to a significant improvement in electron emission.This study lays the groundwork for the next step of developing a discharge-free excitation gas UV light source.