Long Term Retention Characteristic of Small Inverted Dots Formed on Congruent Single-Crystal LiTaO3
- PDF / 2,926,506 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 49 Downloads / 150 Views
0966-T11-21
Long Term Retention Characteristic of Small Inverted Dots Formed on Congruent SingleCrystal LiTaO3 Yasuo Cho1 and Nozomi Odagawa2 1 Research Institute of Electrical Communication, Tohoku University, 2-1-1, Ktahira Aoba-ku, Sendai, 980-8577, Japan 2 Tohoku University, Sendai, 980-8577, Japan
ABSTRACT To investigate the long-term retention characteristics of a ferroelectric-data-storage system, 80-nm-thick congruent LiTaO3 plates with inverted-domain dot arrays composed of 100-nm-φdots were baked at 220, 250, 280 and 300℃. After heat treatment over a range of different time intervals, the dots shrank. From the change in the dot radius data, the activation energy (Ea) and frequency factor (α), parameters of the Arrhenius equation, were determined to be = 0.76 eV, = 2.21×105. From these parameter we can predict competitive retention characteristics compared with general memory devices. The phenomenon of dot shrinking can be explained from the energy transition of the system based on wall energy. INTRODUCTION With current advances in information-processing technology, high-density and highcapacity data storage has become crucial. However, the storage density of magnetic-storage devices, which currently play a major role in this field, will reach a physical limit in the near future. Therefore, alternative high-density data storage systems are required. We have been investigating the potential of using ferroelectric data storage based on scanning nonlinear dielectric microscopy (SNDM) [1]. We have already achieved a storage density of more than 10 Tbit/in.2 with an inverted-domain dot array formed on a single-crystal congruent LiTaO3 (CLT) thin plate [2]. And actual-information-data recording at an areal density of 258 Gbit/in.2 with the bit error rate less than 1 ×10-4 has been reported[3] [4]. Another essential property for the realization of ferroelectric data storage is long-term retention. In an actual memory device, a long-term-data-retention characteristic of over 10 years is required. Therefore, in this study, we investigated the retention characteristics of a nano-domain dot formed on a ferroelectric datastorage medium. To investigate the long-term retention characteristic of data with inverted-domain dots formed on CLT, we conducted a heat-treatment test for following reason. The free energy of a ferroelectric material has two local minimum points. There is an energy barrier between these two local minimum points and the system requires an energy exceeding the energy barrier to erase data associated with the inverted domain dots by switching back the domain. To accelerate the switching back of the domain, we subjected the CLT specimens with inverted-domain-dot arrays to very high temperatures and compared the size of the inverted domain dots before and after the heat treatment.
EXPERIMENT At first, we prepared CLT specimens with thicknesses of 80 nm. Figures 1(a-1), 1(b-1), 1(c-1), and 1(d-1) show images of the inverted-domain dot arrays on the CLT specimens composed of 100-nm-φ dots with center-t
Data Loading...
