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采用基于MS(Materials Studio)软件和密度泛函理论的第一性原理方法,研究了HfO2俘获层的电荷俘获式存储器(Charge Trapping Memory,CTM)中电荷的保持特性以及耐擦写性.在对单斜晶HfO2中四配位氧空位(VO4)缺陷和VO4与Al替位Hf掺杂的共存缺陷体(Al+VO4)两种超晶胞模型进行优化之后,分别计算了其相互作用能、形成能、Bader电荷、态密度以及缺陷俘获能.相互作用能和形成能的计算结果表明共存缺陷体中当两种缺陷之间的距离为2.216时,结构最稳定、缺陷最容易形成;俘获能计算结果表明,共存缺陷体为双性俘获,且与VO4缺陷相比,俘获能显著增大;Bader电荷分析表明共存缺陷体更有利于电荷保持;态密度的结果说明共存缺陷体对空穴的局域能影响较强;计算两种模型擦写电子前后的能量变化表明共存缺陷体的耐擦写性明显得到了改善.因此在Hf O2俘获层中可以通过加入Al杂质来改善存储器的保持特性和耐擦写性.本文的研究可为改善CTM数据保持特性和耐擦写性提供一定的理论指导.
The first-principle method based on MS (Materials Studio) and density functional theory (DFT) was used to study the charge retention and scratch-resistance in charge trapping memory (CTM) After optimization of the two supercell cells models, the four-coordinated oxygen vacancies (VO4) in monoclinic HfO2 and the coexistent defects (Al + VO4) in VO4 and Al-substituted Hf doping, the interaction energy, Formation energy, Bader charge, density of states and trapped energy.The calculation results of the interaction energies and formation energies show that the structure is most stable and the defect is most easily formed when the distance between the two defects is 2.216 共 in the coexistent defect body. The calculation results show that the coexistence defect body is bisexual trapping, and the trapping energy can be significantly increased compared with the VO4 defect. The Bader charge analysis shows that the coexistence defect body is more conducive to the charge retention. The state density results indicate that the coexistence defect body pairs holes The local variation of energies before and after erasing and erasing of the two models shows that the erasure resistance of the coexistent defects is obviously improved and therefore the Hf O2 trapping layer can be improved by adding Al impurities A reservoir holding characteristics and endurance of the study herein may endurance and retention properties of some theoretical guidance for providing improved data CTM.