Analysis of the persistent photoconductivity (PPC) in nanocrystalline Ga2O3/copper-oxide films produced by thermal oxidation at reduced oxygen partial pressure of Ga2O3/copper composite films grown by co-sputtering at room temperature

Abstract Nanocomposite Ga 2 O 3 /copper-oxide films were grown by co-sputtering at room temperature and an oxidation stage at 350 °C in N 2 , to explore their application in resistive gas sensing devices. As commonly observed in metal-oxide films, the samples exhibit persistent photoconductivity (PPC) behavior when exposed to UV radiation. The PPC behavior was explored at 30° C by exposing the samples to UV radiation steps lasting between 5 and 15 min, while the samples were kept in a test chamber under a constant flow of 250 sccm of dry N 2 . The obtained PPC characteristic time constants, τ ON 63 , varied from 6.5 to 11.3 s, while the τ OFF 63 time constants changed from 8.03 to 6.4 s. According to our results, the PPC behavior of Ga 2 O 3 /copper-oxide nanocomposite films is related to the unstable behavior of the energy levels produced by the oxygen vacancies of the samples, rather than the ambient atmosphere of the test chamber. Graphical abstract Persistent photoconductivity (PPC) response at 30 °C in nanocomposite Ga2O3/copper-oxide films exposed to UV radiation steps. The samples were tested in a chamber with 250 sccm flow of dry N2 atmosphere.