Individually addressable, high-density vertical nanotube Schottky diode crossbar array

We report on the fabrication of individually addressable, high-density vertical zinc oxide (ZnO) nanotube Schottky diode arrays. The individually addressable nanotube Schottky diode arrays were fabricated by arranging the top and bottom electrodes in a crossbar configuration on a free-standing layer consisting of position-controlled ZnO nanotubes on graphene films. The electrical characteristics of each Schottky diode in the arrays were investigated by measuring current–voltage characteristics. We also investigated the variation in device characteristics within an array by spatially mapping the barrier height of individual devices. Additionally, we further confirmed the excellent flexibility and electrical robustness of the free-standing and thin Schottky diode arrays under extreme bending conditions and over multiple cycles. Moreover, the photoresponses of the nanotube Schottky diode arrays were investigated by measuring their spectral responses and current–voltage characteristics under light illuminations, yielding a maximum photocurrent to dark current ratio of 1400 and responsivity of 10⁶ A/W. We believe that this work provides a general and rational route for developing many other two-terminal one-dimensional nanostructure device arrays for ultra-high density electronic and optoelectronic devices.