| Budget Amount *help |
¥26,130,000 (Direct Cost: ¥20,100,000、Indirect Cost: ¥6,030,000)
Fiscal Year 2015: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2014: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
Fiscal Year 2013: ¥10,790,000 (Direct Cost: ¥8,300,000、Indirect Cost: ¥2,490,000)
Fiscal Year 2012: ¥7,410,000 (Direct Cost: ¥5,700,000、Indirect Cost: ¥1,710,000)
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| Outline of Final Research Achievements |
We investigated the multilevel storage in phase change memory here. We developed new chalcogenide materials suitable for multilevel storage. By doping N into conventional Sb2Te3, the resistivity gradually drops in a wide range of temperature. This was caused by crystal growth suppression because of the existence of scattered nitrides in the film. 16 resistance levels were demonstrated using a N-doped Sb2Te3 lateral device with a top TiN layer. We also adopted Ge1Sb4Te7 and demonstrated that 27 resistance levels can be obtained using the similar device structure. And cyclability was proved to be possible in this device. GeTe devices exhibited fast speed operation and showed the possibility of multilevel storage. We also investigated how we can obtain the resistance levels using a stair-like programming method. This method was demonstrated that the resistance level can be freely accessible, that is, we can reach any desired resistance levels directly.
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