Organic-ferroelectric oxide memory thin-film transistors (OfeOx-MTFTs) were fabricated using a solution-processed indium-zinc-silicon oxide (IZSiO) active channel and a poly(vinylidene fluoride-trifluoroethylene) ferroelectric gate insulator and characterized to improve device properties such as field-effect mobility (μsat), program speed, and retention time by controlling the IZSiO channel composition. The compositions of IZSiO semiconducting layers were adjusted with different Si amounts of 0, 2, 5, and 10 mol. %. The incorporation of Si in IZSiO channel layer modulated the carrier concentration and reduced defect densities within the channel; among the fabricated OfeOx-MTFT devices, those with IZSiO of 2 mol. % Si content exhibited the best overall performance with μsat, subthreshold swing, memory window, and ratio of on/off programmed currents measured to be 23.3 cm2 V−1 s−1, 772 mV/decade, 11.9 V, and 5.7 × 105, respectively. Incorporating a suitable amount of Si optimized the compromise between the carrier concentration and defect densities within the channel, improving the OfeOx-MTFT program speed and program endurance as well as its data retention properties.