Metal–insulator–semiconductor (MIS) structures based on GeO[SiO] films containing amorphous Ge nanoclusters are fabricated on n+-Si(100) substrate by co-evaporation of GeO2 and SiO powders in ultra-high vacuum. Indium tin oxide (ITO) top electrodes are deposited using magnetron sputtering. According to Raman data, annealing at 500 °C for 20 min leads to an increase in amorphous Ge volume. Current–voltage characteristics provide clear evidence of resistive switching (memristor effect) in the annealed MIS structure after the forming procedure. Both negative and positive photoconductivities are observed in the MIS structure before forming when both negative/positive voltage biases are applied to the top ITO electrode. This is possibly due to light-stimulated recharging of holes originating from Ge-nanoclusters, which act as traps.