Side by side ZnO/ZnS hetero-junction nanocrystal arrays with superior field emission property

ZnO/ZnS hetero-junction nanocone arrays with identical crystallographic orientation have been synthesized using a vapor transport deposition process. The side by side hetero-junction arrays grow on a ZnO basal microflake with an orientation relationship of [0001]ZnO∥[0001]ZnS. The growth mechanism is proposed on the basis of the crystal structure and catalyst theory. ZnO/ZnS hetero-junction nanocone arrays acting as cold electron emitters display excellent field emission performance with the turn-on field as low as 0.02 V μm−1 and the threshold field down to 0.6 V μm−1, also the field-enhancement factor is up to 5.6 × 104. The measured superior emission characteristics, which are even better than carbon nanotubes, could be attributed to the accumulation of electrons inside the mid-layers of the side by side ZnO/ZnS hetero-junction. The new nanoarchitectures could be an important candidate for potential nanoelectronic devices.