Browsing by Author "Nadeem, Muhammad Younus"

Now showing 1 - 3 of 3

Forming-free bipolar resistive switching in nonstoichiometric ceria films
(2014-01-27)
Ismail, Muhammad
;
Huang, Chun-Yang
;
Panda, Debashis
;
Hung, Chung-Jung
;
Tsai, Tsung-Ling
The mechanism of forming-free bipolar resistive switching in a Zr/CeO (x) /Pt device was investigated. High-resolution transmission electron microscopy and energy-dispersive spectroscopy analysis indicated the formation of a ZrO (y) layer at the Zr/CeO (x) interface. X-ray diffraction studies of CeO (x) films revealed that they consist of nano-polycrystals embedded in a disordered lattice. The observed resistive switching was suggested to be linked with the formation and rupture of conductive filaments constituted by oxygen vacancies in the CeO (x) film and in the nonstoichiometric ZrO (y) interfacial layer. X-ray photoelectron spectroscopy study confirmed the presence of oxygen vacancies in both of the said regions. In the low-resistance ON state, the electrical conduction was found to be of ohmic nature, while the high-resistance OFF state was governed by trap-controlled space charge-limited mechanism. The stable resistive switching behavior and long retention times with an acceptable resistance ratio enable the device for its application in future nonvolatile resistive random access memory (RRAM).
Resistive switching characteristics of Pt/CeOx/TiN memory device
(2014-06-01)
Ismail, Muhammad
;
Talib, Ijaz
;
Huang, Chun-Yang
;
Hung, Chung-Jung
;
Tsai, Tsung-Ling
The resistive switching characteristics of Pt/CeOx/TiN memory devices are investigated for potential applications in nonvolatile resistive random access memory (RRAM). The X-ray diffraction characteristics of the sputtered CeOx layer indicate the formation of nanocrystalline single-phase CeO2 with a cubic fluorite structure. The existence of oxygen vacancies in the Pt/CeOx/TiN memory device was determined by X-ray photoelectron spectroscopic studies, while the presence of an interfacial layer between CeOx and the TiN bottom electrode was investigated by Xray diffraction and high resolution transmission electron microscopy. The TiON layer formed at the TiN/CeOx interface seems to play a key role in the resistive switching mechanism of the device. The present CeOx-based device shows excellent bipolar resistive switching characteristics, including a low operation current (100 mu A), high ON/OFF resistance ratio (similar to 10(5)), and good retention/stress characteristics at both room temperature and 85 degrees C. (C) 2014 The Japan Society of Applied Physics
Room-temperature fabricated, fully transparent resistive memory based on ITO/CeO2/ITO structure for RRAM applications
(2015-01-01)
Ismail, Muhammad
;
Rana, Anwar Manzoor
;
Talib, Ijaz
;
Tsai, Tsung-Ling
;
Chand, Umesh
Fully transparent resistive random access memory (TRRAM) device based on Ce02 as active layer using indium-tin-oxide (ITO) electrodes was fabricated on glass substrate. The ITO/CeO2/ITO memory device shows 81% transmission of visible light, optical band gap energy of 4.05 eV, and exhibits reliable bipolar resistive switching behavior. X-ray diffraction of CeO2 thin films demonstrated a weak polycrystalline phase. The low field conduction is dominated by Ohmic type while Poole-Frenkel effect is responsible for conduction in the high field region. The device reliability investigations, such as data retention (over 10(4) s) under applied stress and endurance tests conducted at room temperature and 85 degrees C show potential of our TRRAM devices for future non-volatile memory applications. (C) 2014 Elsevier Ltd. All rights reserved.