Abstract
Research on phase change random access memory (PCRAM) has grown significantly in the past 10 years. PCRAM is based on the resistance switching, which is caused by the phase change triggered by electric pulses. Te-based Ge2Sb2Te5 has received intensive attention for their application to PCRAM due to large sensing margin, rapid phase changes for writing and erasing of data. However, some problems still remain. It is well known that Te is with low melting temperature, high vapor pressure and toxic, which may lead to phase separation within the materials. It has also been noticed that its low crystallization temperature and high melting temperature affects the stability of amorphous state and leads to high reset current during operation. In this study, novel non-chalcogenide Sb-based binary and ternary phase change materials have been investigated, aiming at a chance to replace the commercial Ge2Sb2Te5. We have proposed novel amorphous MgxSb100-x films with new functionality for use in PCRAM due to appropriate characteristics. Both resistivity at crystalline state and crystallization temperature increase with increasing Mg content. These films all show switching phenomena between high and low resistance states. Crystallization kinetics of these films was studied by measuring the temperature dependent electrical resistance during non-isothermal heating. The activation energy (Ea), rate factor (K0) were deduced from Kissinger’s plot. Furthermore, data retention was calculated from the extrapolation of the Arrhenius plot. Mg57Sb43 films exhibited a three-order of magnitude decrease in resistivity, better electrical performance and data retention than Ge2Sb2Te5 does. In the binary Al-Sb system, serious oxidation was encountered during experimental processes, specifically when the aluminum content is high. The crystalline AlSb is instable in air and high reactivity with oxygen and moisture. These drawbacks limit the development of Al-Sb binary alloys. In this study, we focused on the Al16Sb84 film, which remains stable at the amorphous state even after exposuring to air for a month. Al16Sb84 possesses high crystallization temperature(197 ℃) and activation energy(3.74 eV) which is helpful for amorphous stability. In the ternary alloys, metal added Sb-rich InSb is a promising phase change material for 16x rewritable DVD media. In3Sb7 has been selected in this study due to its high crystallization speed and a high thermal stability. According to the experience in the binary Mg-Sb system, we elevated its crystallization temperature and the resistivity of crystalline state successfully by doping magnesium.