Relaxation And Photoconductivity Of TiO₂ Based Resistive Switching Structure

Metal oxides show resistive switching and photoconductivity phenomenon under electric fields and illumination.It has become a frontier research topic in condensed matter physics and has potential applications in the field of information storage.This thesis contain three parts.The first part studied the conduction mechanism of the unformed TiO₂ resistive structure by I-V and low frequency noise measurement.The second and third parts studied the relaxation behavior and photoconductivity of TiO₂ based resistive switching structure.The main research work and results are listed as follows:1.We studied the stability of the resistance measurement of unformed ITO/TiO₂/ITO structure and reproducible results are obtained by improvement of experimental conditions.We investigated the correlation between the forming process and the resistive switching characteristics and discussed the corresponding oxygen vacancy distribution.2.We studied the relaxation behavior of the TiO₂ based resistive switching structure.The results show that for a short time the relaxation of device in high resistance state is ascribed to the detrapping of electrons from the oxygen vacancies near the cathode and the relaxation of device in low resistance state is ascribed to oxygen transport near the anode.For a long time,the current relaxation originates from the slow process of oxygen exchange between TiO_2-x and environment.3.We studied photoconductivity of different resistive structure and found that the photocurrent was attributed to the photoionization of bulk oxygen vacancies.Furthermore,we found that the photocurrent lowering is caused by cooperating oxygen atoms into the device through the sidewall.