Size-dependent field-emission characteristics of ZnO nanowires grown by porous anodic aluminum oxide templates assistance

Abstract: The field-emission electrical properties of hydrothermally synthesized zinc-oxide nanowires grown on SiO2–Si substrate are reported. Vertically aligned single-crystalline emitters with distinct length L and diameter D are realized by controlling the assisted growth of porous anodic aluminum oxide (AAO) templates. Field-emission measurement revealed that these field emitters exhibited controllable turn-on field E to and the field enhancement factor β. Sample with feature size of L =500nm and D =80nm was prepared and then used as a basis for examining the size effect. Lower E to and higher β were observed consistently for increasing the aspect ratio L/D. The enhanced properties of E to =1.48V/μm and β up to 6100 are achieved for L/D =53 (L =1600nm and D =30nm). Optimal characterizing parameters of E to and β will be reached while pursuing extreme L/D practically. Factors such as the geometric limit of AAO template manufacture and the filling efficiency of ZnO into AAO pores will exert influence on the size-dependent effect. [Copyright &y& Elsevier]