Electrical conductivity characterization of zinc oxide seed layer and nanowire by conductive atomic force microscopy

Abstract

Zinc Oxide (ZnO) is a semiconductor nanostructure metal oxide that offers a drastic reduction of energy and electricity consumption by regulating visible transmission. The rapid advancement of ZnO devices however necessitates increased complexity and compact dimensions. This research focused on the deposition and characterization of ZnO seed layer and ZnO nanowire growth. Spin coating technique was used to deposit ZnO seed layers on the silicon substrate. Chemical bath deposition (CBD) technique was used to grow ZnO nanowire with different concentrations between 0 to 1M of Hexamethylenetetramine (HMTA) on silicon substrate. Electrical characterization of ZnO nanowire was measured by conductive atomic force microscopy (C-AFM). C-AFM is considered as a versatile technique to measure the electronic structures at nanoscale. C-AFM was used to determine the local current-voltage characteristic of ZnO of nanowire. Current-voltage characterization revealed a characteristic similar to Schottky diode curve with forward and reverse bias voltage. Moreover, this ZnO nanowire was identified with good rectifying behaviour, small turn on voltage and good ideality factor. The morphology was confirmed by field emission scanning electron microscope (FE-SEM) which showed ZnO nanowire with different patterns according to concentration of HMTA used during nanowire growth process. ZnO nanowire growth with HMTA below 0.03M showed a flower-like pattern with long hexagonal shape. Whereas, ZnO nanowire grown with 0.06M and 0.09M showed long cylindrical shape with uniform diameter around 30-40nm. These properties of ZnO nanowires can be guided to provide opportunity for direct integration of high-performance semiconductor nanoscale devices.