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Copper Sulfide Solid-State Electrolytic Memory Devices

You, Liang
http://rave.ohiolink.edu/etdc/view?acc_num=case1160337918

Abstract Details

2007, Doctor of Philosophy, Case Western Reserve University, Electrical Engineering.
Copper sulfide thin films with electrical switching and memory effect were grown using a chemical vapor reaction apparatus. The formation of copper sulfide film undergoes a process which includes nucleation, growth of nucleation, coalescence into continuous film, and film thickening. The initial phase of the sulfide growth was reaction limited followed by a diffusion limited phase involving out-diffusion of copper. The thin film tends to nucleate and grow at energy favorable sites such as twinning boundary. Sulfidation of polycrystalline copper results in formation of voids at the interface between the copper and its sulfide. (111) copper has the highest sulfidation rate followed by (100) and (110) copper planes. Moreover, the sulfidation rate near the microfabricated plug edge was found to be faster than the rate at the center of the plug. A mechanism based on competing sulfidation sites due to the geometry difference between the plugs’ center and their edge is presented to explain this phenomenon. We show for the first time that field-assisted solid-electrolyte copper sulfide thin film device can function as a switch by reversing the voltage polarity between copper and inert metal electrodes through a copper-sulfide layer in planar and vertical structures. The copper oxide at the top of copper sulfide greatly increased the turn-on voltage. The turn-on voltage depends linearly on the film thickness. Copper sulfide devices in micrometer dimension were microfabricated using IC compatible techniques and characterized showing the same switching effect. Electrode contact area effect on switching performance was investigated in term of turn-on voltage, turn-off voltage, on-state resistance and off-state resistance. Four-point resistance measurement unit, Hall Effect and transfer length measurement were also fabricated together with copper sulfide switching devices and they were studied in order to determine the CuxS carrier type, carrier concentration, film resistivity and contact resistance. An ionic solid state conduction was modeled to mathematically describe the ionic switching effect. This model simulates a copper rich conductive channel propagating in the scope of time and distance with the help chemical potential (composition gradient) as well as electric field.
Massood Tabib-Azar (Advisor)
185 p.
Solid-State Electrolytic; Memory; Microfabrication; Copper Sulfide; MEMS

Recommended Citations

Citations

  • You, L. (2007). Copper Sulfide Solid-State Electrolytic Memory Devices [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1160337918

    APA Style (7th edition)

  • You, Liang. Copper Sulfide Solid-State Electrolytic Memory Devices. 2007. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1160337918.

    MLA Style (8th edition)

  • You, Liang. "Copper Sulfide Solid-State Electrolytic Memory Devices." Doctoral dissertation, Case Western Reserve University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1160337918

    Chicago Manual of Style (17th edition)

case1160337918
3,255
© 2006, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.