Backward-diode heterostructure based on a zinc-oxide nanoarray formed by pulsed electrodeposition and a cooper-iodide film grown by the SILAR method

A heterostructure promising for designing a backward diode is formed from a zinc-oxide nanorod array and a nanostructured copper-iodide film. The effect of modes of successive ionic layer adsorption and reaction (SILAR) deposition and the subsequent iodization of CuI films on smooth glass, mica, and fluorine-doped tin oxide (FTO) substrates and on the surface of electrodeposited nanostructured zinc-oxide arrays on the film structure and electrical and optical properties is investigated. A connection between the observed variations in the structure and properties of this material and intrinsic and iodination-induced point defects is established. It is found that the cause and condition for creating a backward-diode heterostructure based on a zinc-oxide nanoarray formed by pulsed electrodeposition and a copper-iodide film grown by the SILAR method is the formation of a $p^+$-CuI degenerate semiconductor by the excessive iodination of layers of this nanostructured material through its developed surface. The $n$-ZnO/$p^+$-CuI barrier heterostructure, which is fabricated for the first time, has the I – V characteristic of a backward diode, the curvature factor of which ($\gamma$ = 12 V$^{-1}$) confirms its high $Q$ factor.