Fabrication Of Large Interpore Distance PAA Films And Construction Of Nanorod Array Dielectric Capacitors

Porous Anodic Alumina?PAA?templates have been widely used to fabricate the functional nanomaterials.The method of fabricating the small interpore distance PAA films is already known.However,the method of fabricating the large interpore distance PAA films still has many problems,such as the low current density of the anodization,the small growth rate of the alumina films,the rigorous condition of anodization,the accurate control of the temperature and so on.In this work,in order to fabricate the ordered large interpore distance anodic alumina,the species and the proportions of the electrolytes,the voltage,time and temperature of the anodization have been changed.And after the through-hole and enlarge-hole,the large interpore distance anodic alumina template is obtained.Based on this template,the vacuum fusion forced filling method is used to fabricate the aluminum nanorods array.In the end,anodization on the aluminum nanorods array to fabricate the alumina dielectric films and assemble the nanocapacitors.First of all,anodization is reacted in the electrolytes of phosphoric acid and EG-ADP.These electrolytes are composed of deionized water,ethylene glycol and the mixture of different proportions of deionized water and ethylene glycol.Through the comparison of these electrolytes,the mixture of different proportions of deionized water and ethylene glycol plays the best.In this electrolyte,the current density is very large which can achieve almost 300 mA cm^-2 and the anodization can carried out under the room temperature?25??.Meanwhile,the aluminum do not need to polish anymore which simplify the method of fabrication the PAA films.Next,the anodization voltage,the addictives and proportions of deionized water and ethylene glycol are changed to improve the order of the PAA films fabricated in the EG-ADP.The order of the PAA films fabricated in the electrolyte consists of phosphate ester,1 wt%phosphoric acid?addictive?,deionized water and ethylene glycol which proportion is 1:4 is the best.And when the anodization voltage is under 250 V,the larger the voltage is added,the more ordered the PAA films is fabricated.However,when the voltage is over 250 V,although the current density is large,the ordering of the PAA film is decrease with the voltage.Moreover,the barrier layer is removed and chemical etching is used to enlarge the pore distance.The through-hole PAA templates which pore diameter is 400 nm are prepared.The vacuum fusion forced filling method is used to press the aluminum into the PAA template.After adjusting the temperature of adding the pressure,the pressure and the method of staking up the samples,the best condition is decided.It is found that adding the pressure at 580?,keeping the pressure at 1.5 MPa for 10 minutes and then rising the temperature to 650?,the pressure to 2.5 MPa and keeping for 30 minutes can obtain the aluminum nanorods array.In the end,anodization on the aluminum nanorods array can fabricate a piece of dielectric film.And then the dielectric capacitors are fabricated.The properties such as capacitance and leakage current of the aluminum parallel plate capacitor and the aluminum nanorods array dielectric capacitor are tested.The capacitance of the aluminum nanorods array dielectric capacitor is twenty times higher than that of the aluminum parallel plate capacitor.The leakage current is a little bit higher than the parallel plate capacitor.The energy density can improve to 5.56 J cm^-3.