Fabrication and characterization of next-generation inorganic nonvolatile memories

Abstract

Next generation nonvolatile memories (NVMs) such as a ferroelectric random access memory (FRAM), a phase-change random access memory (PRAM), a resistive random access memory (RRAM), and a magnetic random access memory (MRAM) have attracted considerable attention because of their unique advantages when compared to the a dynamic random access memory (DRAM) and a flash memory. Although they are promising candidates for the NVM, there are unsolved problems for the practical applications. In this thesis, ferroelectric tunnel junction (FTJ) is demonstrated for the next-generation NVM with improved performances. The high performance FTJ is realized using semiconductive oxide electrode, which enhances the on/off ratio and develops diode-like property. In addition, a novel neurosynaptic device is proposed for the neuromorphic computing system, which unifies volatile threshold switch and nonvolatile phase change memory in a single device. This threshold switch-phase change memory (TS-PCM) device demonstrates neuronal intrinsic plasticity and synaptic plasiticty in a concomitant manner, emulating biological neuron and synapse simultaneously.