Studies On The Field Response Of Two Data Storage Materials

As the limitations of read-write speed, size and power consumption in FLASH become more apparent, seeking a alternative data storage technique is a growing and important research orientation for electronics giants. Nowadays, there are four crucial non-volatile flash memory alternatives:FeRAM, MRAM, PCRAM and ReRAM. In this thesis we studied on two memorial materials:LiNbO3single crystal and Ge2Sb2Te5alloy. LiNbO3single crystal, as a traditional ferroelectric material, is commonly used for electro-optic modulation, frequency doubling, Pockels cells, optical parametric oscillators, and Q-switching. Ge2Sb2Te5alloy, the typical phase change material, is suitable for non-volatile memories and optical data storage.We focus on the essential application problems of these two materials, that is, ferroelectric domain dynamics of LiNbO3single crystal and crystallization behavior of Ge2Sb2Te5thin films. The main results are as follows:1. Kinetics of linear domains in near-stoichiometric LiNbO3single crystals studied by scanning probe microscope.Linear domains were successfully fabricated using scanning probe pattern technique. It is found that (1) the mean initial domain width linearly increases with the increasing poling voltage and exponentially decreases as the scan velocity increases;(2) As the mean initial domain width decrease, the linear domain would experience stable, partly shrinking, or completely back-switching process, and the critical initial stable domain width increases as the sample thickness augments;(3) To avoid the merging of adjacent linear domains, the distance should be larger than the domain width;(4) Different domain width, irregularity, and roughness were observed in LiNbO3single crystals for domain poling in different crystal orientations. We also found, depending on the area of abnormally switched domains, two distinct interactions between domains manufactured by fixed point poling method in LiNbO3single crystals. For small abnormally switched domain, the tip field applied for fabricating later domain can switch the abnormally switched domain to the tip field direction and further promote the growth of domain edge. For abnormally switched domain with large area, its relaxation process could be speeded up by the tip field applied later.2. Mechanical stress effect on the crystallization behavior of Ge2Sb2Te5thin films.Amorphous Ge2Sb2Te5thin films were fabricated by pulsed laser deposition method and the mechanical stress effect on the crystallization behavior of Ge2Sb2Te5thin films was carefully investigated by electrical resistance measurements. It is found that the crystallization temperature of GST films increases as external compressive stress is applied. For external tensile stress, the crystallization temperature of GST films decreases. We also find that the extrinsic stress can widen the span of transition temperature. These results clearly demonstrate that the mechanical stress plays an important role in the crystallization process of GST films and may further influence the reliability and storage speed of relevant devices.