Controllable Threshold Voltage (Vth) Drift in Ovonic Threshold Switch Devices Under a High-Frequency Continuous Operation

• Published in: IEEE transactions on electron devices Vol. 69; no. 6; pp. 3158 - 3162
• Main Authors: Chen, Ziqi, Wang, Lun, Wen, Jinyu, Tong, Hao, Miao, Xiangshui
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Chalcogenides; Device area; Drift; Heat recovery; Nonvolatile memory; ovonic threshold switch (OTS); pulse falling edge; Pulse measurements; pulse sequence; Switches; Threshold voltage; Weibull distribution
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2022.3169118

In this work, we studied the threshold voltage <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula> for an ovonic threshold switch (OTS) device in a high-frequency continuous operation. By applying a pulse sequence with small pulse intervals, the dependence of <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula> on the falling edge of the prior pulse has been investigated in the Te-based OTS device. The results indicate that the <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula> presents a Weibull distribution in the pulse sequence, and the <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula> distribution drifts nonmonotonically with the pulse falling edge. Meanwhile, the drift tendency of the <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula> distribution was found depending on the device area. Furthermore, the recovery process and the time-resolved current profiles in the device operation have been investigated to further study the <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula> drift. The results indicate that the <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula> drift in continuous device operation is controllable and results from a combination of the effects of heat accumulation and the recovery process. The <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula> drift at high-frequency operating can be reduced by optimizing the device lateral dimension according to the mapping results of the <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula>. Our results can guide the design and operation of the OTS device with a low <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula> drift requirement.