RESUMEN
The electrical properties, resistive switching behavior, and long-term potentiation/depression (LTP/LTD) in a single indium-gallium-zinc-oxide (IGZO) and bi-layer IGZO/ZnO (ZnO: zinc oxide) memristors were investigated for synapse application. The use of the oxide bi-layer memristors, in particular, improved electrical properties such as stability, memristor reliability, and an increase in synaptic weight states. The set voltage of bi-layer IGZO/ZnO memristors was 0.9 V, and the reset voltage was around - 0.7 V, resulting in a low-operating voltage for neuromorphic systems. The oxygen vacancies in the X-ray photoelectron spectroscopy analysis played a role in the modulation of the high-resistance state (HRS) (oxygen-deficient) and the low-resistance state (oxygen-rich) region. The VRESET of the bi-layer IGZO/ZnO memristors was lower than that of a single IGZO, which implied that oxygen-vacancy filaments could be easily ruptured due to the higher oxygen vacancy peak HRS layer. The nonlinearity of the LTP and LTD characteristics in a bi-layer IGZO/ZnO memristor was 6.77% and 11.49%, respectively, compared to those of 20.03% and 51.1% in a single IGZO memristor, respectively. Therefore, the extra ZnO layer in the bi-layer memristor with IGZO was potentially significant and essential to achieve a small set voltage and a reset voltage, and the switching behavior to form the conductive path.
RESUMEN
Gas sensors fabricated using In-Ga-Zn oxide (IGZO) thin films doped with Fluorine (F) were used to detect nitrogen dioxide (NO2) gas. IGZO films with a thickness of 250 nm were deposited onto SiO2/Si substrates via radio-frequency magnetron sputtering, followed by F-doping by an ion-implantation procedure with implant energy of 45 keV and a dose of 3 × 1015 ions/cm2. The NO2 gas detection performance of the fabricated thin-film sensors was tested at various temperatures and NO2 concentrations. The F-doped IGZO (F-IGZO) sensor showed high NO2 gas sensitivity: the ratio between the responses to NO2 and air (Rgas/Rair) was 590 at 250 °C and 100 ppm NO2 gas concentration. F-IGZO sensor showed superior selectivity toward NO2 over other gases. The stability of the sensor was also investigated; the sensor was observed to exhibit stable performance for 2 weeks.
