Fabrication of nitrogen-doped ultrananocrystalline diamond nanowire arrays with enhanced field emission and plasma illumination performance

[[abstract]]Large-area silicon nanowire arrays (SiNAs) were fabricated via metal catalytic etching technique, in conjunction with the polystyrene spheres lithographic process. The nitrogen-doped ultrananocrystalline diamond (N2-UNCD) films were coated on thus formed SiNA by using microwave plasma chemical vapor deposition (MPECVD) process. The N2-UNCD/SiNWs films, which were grown in CH4/N2 plasma at 700°C, possess markedly better conductivity (σN2-UNCD=2-3(Ω cm)-1) than the conventional c-UNCD/SiNWs films, which were grown in CH4/Ar plasma at around 425°C (σUNCD=0.01(Ω cm)-1). The EFE process of the former materials can be turned on at (E0)N2-UNCD=7.80 V/μm achieving larger EFE current density of (Je)N2-UNCD=0.67 mA/cm2 at an applied field of 13.0 V/μm, whereas that of the latter materials need (E0)=UNCD=18.25 V/μm to turn on, attaining only (Je)UNCD=0.024 mA/cm2 at same applied field. While the plasma illumination process can be triggered at around 0.21 V/μm, regardless of the characteristics of the cathod materials, plasma illumination intensity/current density is larger when the materials with better EFE properties were used as cathodes for the plasma device. The plasma illumination current density is around (Jpi)N2-UNCD=5.0 mA/cm2 (at an applied field of 0.35 V/μm) when N2-UNCD/SiNWs film was used as cathode, whereas the (Jpi)UNCD=3.2 mA/cm2 when the conventional UNCD/SiNWs film was used as cathode. In summary, it is observed that the plasma illumination characteristics of the CP-devices is closely correlated with the electron field emission behavior of the cathode materials, which, in turn, was enhanced - ue to the improvement in conductivity of the UNCD films[[conferencedate]]20120709~20120713[[conferencelocation]]Jeju, Kore