Carbon nanotube forest based electrostatic capacitor with excellent dielectric performances

- New design of electrostatic capacitor with metal-insulator-carbon nanotube forest (MIC) configuration.
- CNT forest as electrode to provide a large and accessible specific surface area.
- The sputtered BaTiO3 can penetrated into the CNT forest to form a solid CNT embedded ceramic composite.
- The electrostatic MIC capacitor shows ultrahigh dielectric constant (104 at 0.1 Hz) and high stack capacitance (0.1 Fcm−3).

We demonstrated a new design of electrostatic capacitor with metal-insulator-carbon nanotube forest (MIC) configuration by depositing insulative BaTiO3 (BTO) onto carbon nanotube (CNT) forest electrode through RF magnetron sputtering process. SEM characterization exhibits that the CNT forest with high accessible surface are covered by the compact BTO layer. A giant dielectric constant (104 at 0.1Hz) is achieved by precisely controlling the thickness of BTO layer through varying the time of RF magnetron sputtering process. The quasi-percolation theory is employed to elucidate the dielectric properties of MIC devices. It has been demonstrated that the thickness of BTO layer is a key for the accumulation of space charges at the interfaces between CNTs and BTO, which affords the excellent dielectric performances of capacitors.

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