$n$-ZnO/$p$-CuI barrier heterostructure based on zinc-oxide nanoarrays formed by pulsed electrodeposition and SILAR copper-iodide films

A $p$-CuI/$n$-ZnO barrier structure is investigated as a promising base diode structure for a semitransparent near-ultraviolet detector. We analyze the crystal structure and electrical and optical properties of zinc-oxide nanoarrays electrodeposited in the pulsed mode and copper-iodide films formed by the successive ionic layer adsorption and reaction (SILAR) method, which were used as the basis for an $n$-ZnO/$p$-CuI barrier heterostructure sensitive to ultraviolet radiation in the spectral range of 365–370 nm. Using the I–V characteristics, a shunting resistance of $R_{sh}\cdot S_c$ = 879 $\Omega$ cm$^2$, a series resistance of $R_s\cdot S_c$ = 8.5 $\Omega$ cm$^2$, a diode rectification factor of $K$ = 17.6, a rectifying $p$–$n$-junction barrier height of $\Phi$ = 1.1 eV, and a diode ideality factor of $\eta$ = 2.4 are established. It is demonstrated that at low forward biases (0 $<U<$ 0.15 V), the effects of charge-carrier recombination and tunneling are equal. As the bias increases above 0.15 V, the tunneling–recombination transport mechanism starts working. The diode saturation current $J_0$ is found to be 6.4 $\times$ 10$^{-6}$ mA cm$^{-2}$ for recombination and tunneling charge-carrier transport and 2.7 $\times$ 10$^{-3}$ mA cm$^{-2}$ for tunneling–recombination charge-carrier transport.