Large-Area Schottky Junctions between ZnO and Carbon Nanotube Fibres

In this study, large-area (10 cm² ) samples of heterojunctions between zinc oxide and carbon nanotube (CNT) fibre arrays were synthesised. A two-step hydrothermal treatment was used to grow Zn nanowires (NWs) in situ directly onto the CNT array. This resulted in a bulk heterojunction that consisted of a five-micron layer of ZnO crystals in contact with the built-in CNT fabric current collector, with preferential orientation of the ZnO c axis perpendicular to the CNT sheet. The electrical properties of the heterojunction corresponded to a Schottky junction with a barrier height of 0.26 eV and an ideality factor of 2.9. Photoconductivity measurements indicated charge transfer through the ZnO/CNT interface, thus leading to a gain factor of approximately 100 and a responsivity as high as 5000 mA w^-1 under UV irradiation. The resulting ZnO/CNT fibre hybrid was both piezoresistive and piezoelectric under transverse compression with an attractive format for energy-harvesting applications.