University of Twente Student Theses


Structure and functionality correlation in resistive random access memory devices

Berg, T. van den and Hack, M. (2015) Structure and functionality correlation in resistive random access memory devices.

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Abstract:Resistive random access memory (RRAM) is a form of memory. RRAM devices are able to switch between two resistance states, making it useful for data storage. RRAM devices typically consist of a metal-oxide sandwiched between two metal electrodes. In this report the effect of the oxygen pressure during PCMO growth on device performance is researched using Au/Ti/PCMO/SRO/Nb-STO/Ti/Au devices. Using AFM and XRD the influence of oxygen pressure on the structural properties of the PCMO was researched. It was found that the crystallinity of the PCMO layer increases as the oxygen pressure is increased. Devices in which PCMO was grown at low oxygen pressure seem to perform better than those in which PCMO was grown at higher oxygen pressure. The influence of the applied signal on the stability of the device was also researched. A sweep signal and a signal of which the total voltage sum is zero lead to the best device stability. While the HRS/LRS-ratio of all three devices was sufficient to compete with flash memory, the stability and retention of the devices was not. The compatibility of PCMO-based RRAM with current CMOS technology was also researched. Two devices were grown on silicon substrates. One device (Au/Ti/PCMO/Pt/Ti/SiO2/Si) did not show resistive switching behaviour. The other device (Au/Ti/PCMO/SRO/STO/Si) does show resistive switching behaviour. This might be caused by the (110) orientation the PCMO in the Pt/Ti/SiO2 /Si-based device. The orientation of the PCMO in the SRO/STO/Si-based device is (002), which is also the orientation used in the devices used for the oxygen pressure measurements. The latter device converges to a HRS/LRS-ratio of approximately 3 after 1000 switching cycles. Hence, functioning PCMO-based RRAM devices can be grown on silicon substrates, meaning that they are compatible with current CMOS technology.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Subject:51 materials science
Programme:Applied Physics BSc (56962)
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