Electron emission of silicon field emitter arrays coated with N-doped SrTiO₃ film

Nitrogen doped SrTiO₃ (STO) thin films have been fabricated on Si field emitter arrays (FEAs) using reactive RF magnetron sputtering in Ar-N₂ mixture ambient for electron emission applications. The nitrogen incorporation in STO films was revealed both in Fourier transform infrared (FTIR) spectroscopy and in Auger electron spectroscopy (AES). Low dose incorporation of nitrogen in STO films shows enhanced crystallinity, whereas the overdosed films show the degraded perovskite structure. The results demonstrate that the threshold emission field is lowered tremendously from 36.24 V/μm for uncoated FEAs to 17.37 V/μm for 30-nm-thick STO coated FEAs deposited in 50% N₂ ambient. The enhanced electron emission characteristics are highly correlated with the nitrogen incorporation in STO and film thickness. The substitution of nitrogen for oxygen may result in the band-gap narrowing in STO with enhanced electron emission. The thickness dependence might be related to the formation of space-charge-induced band-bending interlayer at STO/Si interface.