Origin of the Low-Frequency 1/f Noise of a Photoelectrochemical Photodetector

The low-frequency photocurrent noise power density
${S}_{I}$
of a self-powered photoelectrochemical photodetector (PEC PD) based on InGaN/Cu2O core–shell nanowire p-n junctions follows a 1/
${f}^{\beta }$
frequency dependence. The exponent
$\beta $
increases from 1.5 to about 2 with increase of the photocurrent density
${I}_{p}$
.
${S}_{I}$
strongly deviates from the standard quadratic
${I}_{p}$
dependence with an exponent of 1.6. The noise behavior of the dark current density driven by an external voltage is very similar.
$\beta $
distinctly depends on the NaI electrolyte concentration. Hence, the physical origin of the low-frequency 1/
${f}^{\beta }$
noise is the redox noise generated by the Faradaic charge transfer at the electrode-electrolyte interface. The redox noise dominates the total noise of the PEC PD.