| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 100 === A thin copper-doped tantalum oxide (Cu-TaOx) film was prepared by plasma oxidation of a copper-doped tantalum nitride (Cu-TaN), and its resistance switching behavior was studied. A Cu-TaN film was firstly deposited by co-sputtering as a bottom electrode, then the Cu-TaN film was oxidized in an oxygen-containing plasma to form an insulating layer (Cu-TaOx). At last, the TaN film was deposited on top of the insulating layer as the top electrode to form a MIM structure.
The insulating layer was fabricated by RF plasma oxidation and microwave plasma oxidation, respectively. Both of these two devices exhibited bipolar resistance switching when DC voltages were swept. And the resistance ratio of RHRS/RLRS measured at +0.3 V were above 10 to 100 using two different compliant currents. This phenomenon suggested that conducting filamentary paths may form inside the Cu-TaOx layer.
In the microwave plasma oxidation, the device showed Schottky emission in the low voltage region of HRS, and exhibited poole-frenkel emission in the high voltage region of HRS, whereas LRS followed SCLC mechanism.
In the contrast, when the insulating layer was formed by RF plasma oxidation, the device showed SCLC mechanism in HRS and Ohmic contact in LRS, respectively.
The insulating layers made by two different oxidization methods were examined by XPS, SEM and TEM. Different compositions and structures were revealed in the insulating layer, causing different conducting mechanism in the I-V analysis.
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