Sol–gel-processed Y₂O₃ films were used as active channel layers for resistive random access memory (RRAM) devices. The fabricated ITO/Y₂O₃/Ag RRAM devices exhibited the properties of conventional bipolar memory devices. A triethylamine stabilizer with a high vapor pressure and low surface tension was added to realize the local electric field area. During drying and high-temperature post-annealing processes, the large convective flow enhanced the surface elevation, and the increased –OH groups accelerated the hydrolysis reaction and aggregation. These phenomena afforded Y₂O₃ films with an uneven surface morphology and an increased surface roughness. The increased roughness of the Y₂O₃ films attributable to the triethylamine stabilizer enhanced the local electrical field, improved device reliability, and achieved successful repetition of the switching properties over an extended period.

Flexible indium tin oxide (ITO)/Y₂O₃/Ag resistive random access memory (RRAM) devices were successfully fabricated using a thermal-energy-free ultraviolet (UV)/ozone-assisted photochemical annealing process. Using the UV/ozone-assisted photochemical process, the organic residue can be eliminated, and thinner and smother Y₂O₃ films than those formed using other methods can be fabricated. The flexible UV/ozone-assisted photochemical annealing process-based ITO/Y₂O₃/Ag RRAM devices exhibited the properties of conventional bipolar RRAM without any forming process. Furthermore, the pure and amorphous-phase Y₂O₃ films formed via this process showed a decreased leakage current and an increased high-resistance status (HRS) compared with the films formed using other methods. Therefore, RRAM devices can be realized on plastic substrates using a thermal-energy-free UV/ozone-assisted photochemical annealing process. The fabricated devices exhibited a resistive window (ratio of HRS/low-resistance status (LRS)) of >10⁴, with the HRS and LRS values remaining almost the same (i.e., limited deterioration occurred) for 10⁴ s and up to 10² programming/erasing operation cycles.

Sol-gel processed SnO₂ thin-film transistors (TFTs) were fabricated on SiO₂/p₊ Si substrates. The SnO₂ active channel layer was deposited by the sol-gel spin coating method. Precursor concentration influenced the film thickness and surface roughness. As the concentration of the precursor was increased, the deposited films were thicker and smoother. The device performance was influenced by the thickness and roughness of the SnO₂ active channel layer. Decreased precursor concentration resulted in a fabricated device with lower field-effect mobility, larger subthreshold swing (SS), and increased threshold voltage (V_th), originating from the lower free carrier concentration and increase in trap sites. The fabricated SnO₂ TFTs, with an optimized 0.030 M precursor, had a field-effect mobility of 9.38 cm²/Vs, an SS of 1.99, an I_on/I_off value of ~4.0 × 10⁷, and showed enhancement mode operation and positive V_th, equal to 9.83 V.

In this study, sol–gel-processed Li-doped SnO₂-based thin-film transistors (TFTs) were fabricated on SiO₂/p+ Si substrates. The influence of Li dopant (wt%) on the structural, chemical, optical, and electrical characteristics was investigated. By adding 0.5 wt% Li dopant, the oxygen vacancy formation process was successfully suppressed. Its smaller ionic size and strong bonding strength made it possible for Li to work as an oxygen vacancy suppressor. The fabricated TFTs consisting of 0.5 wt% Li-doped SnO₂ semiconductor films delivered the field-effect mobility in a 2.0 cm²/Vs saturation regime and I_on/I_off value of 1 × 10⁸ and showed enhancement mode operation. The decreased oxygen vacancy inside SnO₂ TFTs with 0.5 wt% Li dopant improved the negative bias stability of TFTs.