Search

An electric-field induced phase transition between semiconducting 2H and metallic 1T′ phases in a MoTe2 device is demonstrated for the first time. The phase transition exhibits faster switching compared with phase-change random-access memory (PCRAM), and shows more controllable switching than conventional memristive devices.

In-memory computing based on memristive logic is considered as a prospective non von Neumann computing paradigm. In this letter, we systematically analyze the four-variable logic method and map it into the operation of two anti-serial complementary memristors in the crossbar array architecture. Arbitrary Boolean logic can be implemented within three cycles with the experimental evidence of reconfigurable NAND, NOR, and XOR logic using Pt/HfO2/TiN devices. Taking advantage of the functional flexibility, a parallel 1-bit full adder that can be realized in 8 cycles within a $\textsf {4}\times \textsf {3}$ array has been designed and verified in simulation.

The next-generation nonvolatile memory storage may well be based on resistive random access memories (RRAMs). $$\hbox {TiO}_{2}$$ and $$\hbox {HfO}_{2}$$ have been widely used as the resistive switching layer for RRAM devices. However, the electronic properties of the filament-to-dielectric interfaces are still not well understood yet, compared to those of the electrodes and the dielectric. In this work, we study the electronic structures of three typical filament and dielectric structures, $$\hbox {Ti}_{4}\hbox {O}_{7}/\hbox {TiO}_{2}$$ , $$\hbox {Hf}_{2}\hbox {O}_{3}/\hbox {HfO}_{2}$$ and $$\hbox {Hf}/\hbox {HfO}_{2}$$ , using ab initio calculations. We implement the GGA-1/2 method, which rectifies the band gaps of GGA through self-energy correction. Our calculation predicts an ohmic contact for the $$\hbox {Ti}_{4}\hbox {O}_{7}/\hbox {TiO}_{2}$$ interface, where the defective $$\hbox {Ti}_{4}\hbox {O}_{7}$$ phase was experimentally identified as the filament composition in $$\hbox {TiO}_{2}$$ . However, there is a finite Schottky barrier existing in either $$\hbox {Hf}_{2}\hbox {O}_{3}/\hbox {HfO}_{2}$$ interface (1.96 eV) or $$\hbox {Hf}/\hbox {HfO}_{2}$$ interface (0.61 eV), the two probable filament–dielectric configurations in hafnia-based RRAM. Our results suggest that the distinct filament-to-dielectric band alignments in $$\hbox {TiO}_{x}$$ and $$\hbox {HfO}_{x}$$ systems account for the much larger resistance window for the latter.

Nonvolatile stateful logic through RRAM is a promising route to build in-memory computing architecture. In this letter, a logic methodology based on 1T1R structure has been proposed to implement functionally complete Boolean logics. Arbitrary logic functions could be realized in two steps: initialization and writing. An additional read step is required to read out the logic result, which is in situ stored in the nonvolatile resistive state of the memory. Cascade problem in building larger logic circuits is also discussed. Our 1T1R logic device and operation method could be beneficial for massive integration and practical application of RRAM-based logic.