Self-Compliance Current Limited Transition Metal Oxide Based ReRAM Devices and Applications

Bibliographic Details
Main Author:	Lu, Wenchao
Language:	English
Published:	University of Toledo / OhioLINK 2016
Subjects:	Electrical Engineering Engineering
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=toledo1467323013

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-toledo14673230132021-08-03T06:37:07Z Self-Compliance Current Limited Transition Metal Oxide Based ReRAM Devices and Applications Lu, Wenchao Electrical Engineering Engineering Transition metal oxide (TMO) based ReRAM devices have been studied for nonvolatile memory (NVM) applications due to their two-terminal configuration, fast switching speeds, excellent scalability, and process compatibility with complementary metal–oxide–semiconductor (CMOS) technology [1-6]. However, TMO ReRAM typically needs high electroforming voltage to form a filament and initiate switching between high (HRS) and low resistance states (LRS) [7-11]. A high electroforming voltage not only limits the scalability, but also worsens the overshoot in compliance current (CC) due to any parasitic capacitances (Cp). The overshoot in CC causes uncontrolled formation of the filament that leads to variability in devices. It also adversely affects reliability and endurance. In current ReRAM devices, a precise CC control is achieved using an on-chip transistor during electroforming and set operations, which limits the scalability of ReRAM [12-18]. The emergence of 2-dimensional (2-D) materials provides a unique opportunity to evaluate their application in the areas of ReRAM devices as a viable route to modulate interfaces and achieve desired device characteristics [19]. To address these issues, we have studied the impact of inserting an ultra-thin layer of Transition Metal Disulfide (TMD) material based on WS2 as interfacial layer (IL) in TMO based ReRAM devices. Layered TMD films, such as WS2 and MoS2, have also gathered significant interest for their potential to demonstrate fascinating electronic and optoelectronic properties when confined in ultra-thin 2-D atomic layer thicknesses [20-22]. Our studies show that the insertion of WS2 layer reduces the forming voltage to ~1.2 V and the reset current by 12 times when compared to devices without WS2 IL. However, this comes at the cost of compromising endurance of the devices. The physics behind these observations is investigated and reported in this work. This fundamental study opens the possibilities for optimizing the TMO/TMD stacks in order to achieve low-switching energy ReRAM devices. Moreover, recent research focuses on self-compliance controlled (SCC) ReRAM devices i.e. devices that do not need any CC control during electroforming or set operations [23-29]. Based on this inspiration, we have studied the performance of SCC and forming-free MgO based ReRAM devices. MgO based ReRAM devices have been reported to show nonpolar and bipolar switching [30, 31] and, therefore, serve as an excellent platform for evaluating the impact of interfacial layer (IL) for SCC. In our work, the SCC property in MgO-ReRAM is achieved by interface engineering using Ti and TiOx ILs. Our studies indicate that both Ti and TiOx can result in SCC switching in MgO ReRAM devices with low set and reset voltages. However, switching current was observed to be much lower for TiOx IL compared to Ti IL. Interestingly, the set current decreases and uniformity of devices improves with increase in the thickness of TiOx IL up to a certain limit (~7nm). Mechanisms behind this observation are explained and supported with results from Capacitance-Voltage (CV) measurements. 2016 English text University of Toledo / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=toledo1467323013 http://rave.ohiolink.edu/etdc/view?acc_num=toledo1467323013 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection	NDLTD
language	English
sources	NDLTD
topic	Electrical Engineering Engineering
spellingShingle	Electrical Engineering Engineering Lu, Wenchao Self-Compliance Current Limited Transition Metal Oxide Based ReRAM Devices and Applications
author	Lu, Wenchao
author_facet	Lu, Wenchao
author_sort	Lu, Wenchao
title	Self-Compliance Current Limited Transition Metal Oxide Based ReRAM Devices and Applications
title_short	Self-Compliance Current Limited Transition Metal Oxide Based ReRAM Devices and Applications
title_full	Self-Compliance Current Limited Transition Metal Oxide Based ReRAM Devices and Applications
title_fullStr	Self-Compliance Current Limited Transition Metal Oxide Based ReRAM Devices and Applications
title_full_unstemmed	Self-Compliance Current Limited Transition Metal Oxide Based ReRAM Devices and Applications
title_sort	self-compliance current limited transition metal oxide based reram devices and applications
publisher	University of Toledo / OhioLINK
publishDate	2016
url	http://rave.ohiolink.edu/etdc/view?acc_num=toledo1467323013
work_keys_str_mv	AT luwenchao selfcompliancecurrentlimitedtransitionmetaloxidebasedreramdevicesandapplications
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Self-Compliance Current Limited Transition Metal Oxide Based ReRAM Devices and Applications

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