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Conmutación resistiva inducida eléctricamente en películas delgadas de V4O7/SiO2
Lozano Arroyo, Manuel Alejandro
Lozano Arroyo, Manuel Alejandro
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Abstract
Películas delgadas de V4O7 de 150 nm de grosor fueron crecidas sobre sustratos de SiO2 mediante la técnica de sputtering reactivo por magnetrón DC. Picos característicos de V4O7 fueron confirmados por difracción de rayos X. La morfología de las muestras fue estudiada por microscopía de fuerza atómica y de rastreo. El tamaño de grano promedio fue ~ 0.6 μm, y los valores promedio de la rugosidad 35 nm. Se realizaron medidas de conductividad en función de la temperatura utilizando la técnica de Van der Pauw. Las películas exhibieron una transición metal aislante a una temperatura cercana a 237 K y un cambio en la conductividad de dos órdenes de magnitud, resultados similares a los del mismo material en grueso.
Se utilizaron técnicas de litografía en la fabricación de dispositivos con diferentes dimensiones depositando electrodos metálicos de Au/Cr sobre las películas delgadas de V4O7/SiO2. Los dispositivos se caracterizaron eléctricamente mediante diagramas de voltaje y corriente en un rango de temperaturas de 150 K hasta temperatura ambiente. En las medidas realizadas a temperaturas mayores de 240 K se observó que los dispositivos obedecían la Ley de Ohm. Sin embargo, a una temperatura menor de 240 K se observaron cambios en la resistencia del material, propios del fenómeno de conmutación resistiva. Las curvas de voltaje y corriente, y la dependencia de la conmutación resistiva con la temperatura en los diferentes dispositivos, indican que parte de este fenómeno ocurre debido al calentamiento por el efecto Joule.
V4O7 thin films of 150 nm thickness were grown onto SiO2 substrates using the reactive DC magnetron sputtering technique. Characteristic peaks of V4O7 were confirmed by X-ray diffraction. The morphology of the samples was studied by scanning and atomic force microscopy. The average grain size was ~0.6 μm, and the average roughness values of 35 nm. Conductivity measurements as a function of temperature were performed using the Van der Pauw technique. The films exhibited an insulating metal transition and a two-order-of-magnitude change in conductivity at temperatures close to 237 K, similar to those reported for the bulk of the same material. Lithography techniques were used to fabricate devices with different dimensions by depositing metallic Au/Cr electrodes onto the V4O7/SiO2 thin films. The devices were electrically characterized using voltage and current diagrams over a temperature range from 150 K to room temperature. In the measurements made at temperatures greater than 240 K, it is observed that the devices obey Ohm's Law. However, at a temperature lower than 240 K changes in the resistance of the material typical of the resistive switching phenomenon were observed. The voltage and current curves and the dependence of the resistive switching on temperature in the devices, with different separations between the electrodes, indicate that part of this phenomenon occurs due to heating by the Joule effect.
V4O7 thin films of 150 nm thickness were grown onto SiO2 substrates using the reactive DC magnetron sputtering technique. Characteristic peaks of V4O7 were confirmed by X-ray diffraction. The morphology of the samples was studied by scanning and atomic force microscopy. The average grain size was ~0.6 μm, and the average roughness values of 35 nm. Conductivity measurements as a function of temperature were performed using the Van der Pauw technique. The films exhibited an insulating metal transition and a two-order-of-magnitude change in conductivity at temperatures close to 237 K, similar to those reported for the bulk of the same material. Lithography techniques were used to fabricate devices with different dimensions by depositing metallic Au/Cr electrodes onto the V4O7/SiO2 thin films. The devices were electrically characterized using voltage and current diagrams over a temperature range from 150 K to room temperature. In the measurements made at temperatures greater than 240 K, it is observed that the devices obey Ohm's Law. However, at a temperature lower than 240 K changes in the resistance of the material typical of the resistive switching phenomenon were observed. The voltage and current curves and the dependence of the resistive switching on temperature in the devices, with different separations between the electrodes, indicate that part of this phenomenon occurs due to heating by the Joule effect.
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2023-01-30
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Keywords
Neuromorphic Computing, Vanadium oxides, Thin film deposition, Thin film characterization, Lithography