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

Abstract

This study proposes a bipolar resistive random-access memory (RRAM), which is fabricated using an aluminum oxide (AlOx) resistive switching (RS) layer. The RRAM shows a large memory window of 106 at a low read voltage of 0.5 V. In addition, high switching speed, high data retention capability, and superior read-disturb immunity are observed. AlOx layers are prepared by a thermal oxidation growth process. Aluminum metal films deposited on n+-Si wafers are oxidized at O2/(O2+N2) flow rate ratios of 50-100%. Al/AlOx/n+-Si device shows no RS behavior when the AlOx is grown in a pure O2 environment. As the O2/(O2+N2) flow rate ratio decreases to 50%, Al/AlOx: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 AlOx devices prepared at different O2 flow rates.