Effect of Annealing on the Electron Field-Emission Properties ofZnO Nanowires

D.F. Wang, S.Y. Park, T.W. Eom, Y.P. Lee and J.C. Li

J. Korean Phys.Soc. 53,2710 [doi: 10.3938/jkps.53.2710 | PDF Download]

\vspace{-0.2cm}The electron field-emission characteristics of ZnO nanowires with adiameter of about 20 nm grown on a $p$-type silicon (100) substratehave been investigated. The ZnO nanowires were synthesized by usingthermal evaporation with subsequent annealing at 500 -- 800$^\circ$C in air. We found that the field-emission properties wereimproved significantly after annealing. The threshold electric fieldwas decreased after annealing to 3.2 V/$\mu$m for the sampleannealed at 700 $^\circ$C, compared to 5.8 V/$\mu$m for the as-grownsample. The minimum emission current (1 mA/cm$^2$), producing aluminance of 300 cd/m$^2$ for a video graphic array field-emissiondisplay with a high-voltage phosphor-screen efficiency of 9 lm/W,was achieved under an electric field of 7.4 V/$\mu$m for the sampleannealed at 700 $^\circ$C, compared to 10.2 V/$\mu$m for theas-grown sample. To understand the underlying mechanism, we measuredthe photoluminescence (PL) at room temperature. The PL analysisrevealed that the field emission properties of ZnO nanowire dependedstrongly on the intrinsic defects.