Nanoscale Cross‐Point Resistive Switching Memory Comprising p‐Type SnO Bilayers

Alternative architectures and materials for future memory devices are of particular interest because complimentary metal-oxide-semiconductor (CMOS) technologies are expected to reach their limits in the next decade. Among many candidates to replace the existing memory devices, resistance random access memory (RRAM) is assumed to be one of the promising candidates owing to its simple metal–insulator–metal structure, fast switching speed, low-power operation, excellent scalability potential, and high density along with its ability to combine the key features of established Flash, static random access memory (SRAM) and dynamic random access memory (DRAM) memory performances. [ 1–3 ] In general, the resistive switching memory devices show reproducible switching between high resistance state (HRS) and low resistance state (LRS) during one DC voltage sweeping cycle. In contrast, resistive switching devices have been categorized into two types, i.e., the bias amplitude dependent unipolar switching and the bias polarity dependent Reproducible low-voltage bipolar resistive switching is reported in bilayer structures of p-type SnO fi lms. Specifi cally, a bilayer homojunction comprising SnO x (oxygen-rich) and SnO y (oxygen-defi cient) in nanoscale cross-point (300 × 300 nm 2 ) architecture with self-compliance effect is demonstrated. By using two layers of SnO fi lm, a good memory performance is obtained as compared to the individual oxide fi lms. The memory devices show resistance ratio of 10 3 between the high resistance and low resistance states, and this difference can be maintained for up to 180 cycles. The devices also show good retention characteristics, where no signifi cant degradation is observed for more than 10 3 s. Different charge transport mechanisms are found in both resistance states, depending on the applied voltage range and its polarity. The resistive switching is shown to originate from the oxygen ion migration and subsequent formation/rupture of conducting fi laments.