Nonvolatile bipolar resistive switching characteristics of aluminum oxide grown by thermal oxidation processes

This study proposes a bipolar resistive random-access memory (RRAM), which is fabricated using an aluminum oxide (AlO x ) resistive switching (RS) layer. The RRAM shows a large memory window of 10 6 at a low read voltage of 0.5 V. In addition, high switching speed, long retention time, and superior read-disturb immunity are observed. AlO x layers are prepared by a thermal oxidation growth process. Aluminum metal films deposited on n + -Si wafers are oxidized at O 2 /(O 2 + N 2 ) flow rate ratios of 50%–100%. Al/AlO x /n + -Si device shows no RS behavior when the AlO x is grown in a pure O 2 environment. As the O 2 /(O 2 + N 2 ) flow rate ratio decreases to 50%, Al/AlO x :N/n + -Si device reveals stable bipolar RS characteristics. A filamentary mode based on oxygen interstitial and Al vacancy is proposed to explain the difference in electrical characteristics of AlO x devices prepared at different O 2 flow rates.