Facile fabrication of SWCNT/SnO₂ nanowire heterojunction devices on flexible polyimide substrate

We report on the fabrication and electronic properties of single-walled carbon nanotube (SWCNT)/tin oxide nanowire (SnO₂ NW) heterojunction device arrays on flexible polyimide (PI) substrates. Hetero-NW junctions consisting of crossed SnO₂NWs and SWCNTs were fabricated by sliding transfer of SnO₂ NWs onto the SWCNT channels on PI substrate. Individual SWCNTs and SnO₂ NWs field effect transistors showed p- and n-type transfer properties with current on/off ratios of 7.0 × 10 ⁵ and 2.7 × 10⁶, respectively. The heterojunction diode showed a rectifying behavior with a rectification ratio of higher than 10³ at ±1 V and the analysis with an equivalent circuit model of serially connected diode and resistor estimated an ideality factor of 1.5 and the resistance of 20 MΩ. The rectification of AC input signal was clearly demonstrated by fabricating a full-wave bridge circuit of heterojunctions. In addition, the heterojunctions showed a high UV photosensitivity of ~ 10 ⁴ under reverse bias, suggesting their implicit applications inUV sensors.