| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 104 === In this thesis, we demonstrate a new device mechanism and material system for realizing phase change memory (PCM). We combine two device concepts into one single device, i.e., phase change memory and resonant tunneling diode. Metal oxide were used as the phase changing material, unlike the conventional GeSbTe material. Our devices was prepared by the Plasma-Enhanced Atomic Layer Deposition (PEALD) system, with a double-barrier quantum-well structure.
There are two main parts in this thesis. First, we introduce how to make our memory device, including the mechanism and operation of PE-ALD, the calibration of growth rate and X-ray photoelectron spectroscopy analysis of each material, and the whole device fabrication process. Second, we discuss the electrical measurements, including characteristic I-V curves, comparison of threshold powers for phase change, relationship between set and reset conditions, and life-time cycling test.
Oxide stacks of HfO2/ZnO/HfO2 (2/4/2, 2/6/2 nm) and Ga2O3/ZnO/HfO2 (4/2/4, 4/3/4 and 4/4/4 nm) were deposited by PE-ALD, and devices of 625π, 3025π, 7225π and 11025π 〖μm〗^2 were fabricated. We found that Ga2O3/ZnO/HfO2 (4/2/4) device of area 625π 〖μm〗^2 has the best properties for PCM device: lowest threshold power of ~ 2.6 mW, highest resistance on/off ratio of ~ 1000, and more than 100 times operation in life-time cycling test.
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