ZnO and ZnO1−x based thin film memristors: The effects of oxygen deficiency and thickness in resistive switching behavior

Abstract

In this study, direct-current reactive sputtered ZnO and ZnO1-x based thin film (30 nm and 300 nm in thickness) memristor devices were produced and the effects of oxygen vacancies and thickness on the memristive characteristics were investigated. The oxygen deficiency of the ZnO1-x structure was confirmed by SIMS analyses. The memristive characteristics of both the ZnO and ZnO1-x devices were determined by time dependent current-voltage (I-V-t) measurements. The distinctive pinched hysteresis I-V loops of memristors were observed in all the fabricated devices. The typical homogeneous interface and filamentary types of memristive behaviors were compared. In addition, conduction mechanisms, on/off ratios and the compliance current were analyzed. The 30 nm ZnO based devices with native oxygen vacancies showed the best on/off ratio. All of the devices exhibited dominant Schottky emissions and weaker Poole-Frenkel conduction mechanisms. Results suggested that the oxygen deficiency was responsible for the Schottky emission mechanism. Moreover, the compliance currents of the devices were related to the decreasing power consumption as the oxygen vacancies increased.

Emulator Circuits and Resistive Switching Parameters of Memristor

“…It is expected that the memristor device's distribution of the HRS or LRS state which is shown in Figure 10 has acceptable values besides its ON/OFF ratio [19]. Since the memory unit needs to be repeatedly read or written by the other control units, cycling endurance is one of the main importance of memristor-based memory devices [18].…”

“…Since the memory unit needs to be repeatedly read or written by the other control units, cycling endurance is one of the main importance of memristor-based memory devices [18]. Some of recent memristor devices which are composed of various materials are compared according to the some important parameters as shown in Table 1 [19,[22][23][24]. The chapter is continued with memristor emulators based on the active circuit elements.…”

“…With the aim of escape permanent damage from over current, the compliance or limit current (CC) must be set in both unipolar and bipolar operations [13]. The compliance current is also related to power consumption of a memristor device [19].…”

Mathematical Modeling of Memristors

“…where R on and R off are the values of the resistance for w(t) = D and w(t) = 0, respectively [2,8,9].…”

“…The memristor structures produced from different materials can be given as example, such as titanium dioxide (TiO 2 ) memristor [2], zinc oxide memristor [8,9], silicon oxide memristor [10], and GST (Ge 2 Sb 2 Te 5 ) memristor [11].…”