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首页> 外文期刊>Physical review >Generation Of Vacancy-interstitial Pairs As A Possible Origin Of Resistivity Switching Andrnferroelectric Properties In Cd_(1-x)zn_xte
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Generation Of Vacancy-interstitial Pairs As A Possible Origin Of Resistivity Switching Andrnferroelectric Properties In Cd_(1-x)zn_xte

机译：空位-间隙对的产生是Cd_（1-x）zn_xte中电阻率转换和铁电性质的可能起源

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Formation of vacancy-interstitial Frenkel pairs, together with the properties of interstitials and vacancies in CdTe, ZnTe, and their alloys were investigated by first-principles calculations. Generation of Frenkel pairs on the cation sublattice strongly depends on the Fermi energy: the presence of excess free electrons reduces the energy barrier for the pair generation from 2.5 eV in intrinsic samples to 1.2 eV. Moreover, E_F determines both the stability of Frenkel pairs with respect to recombination and their binding energy, which varies from ～0.2 to ～ 1 eV. A strong dependence on the Fermi energy, i.e., on the charge state, is also found for stable sites and barriers for diffusion of isolated interstitials. In particular, neutral interstitials have two (meta)stable sites, corresponding to two local minima of energy, and diffuse by jumps between them. Positively charged interstitials have only one stable site and diffuse by twice longer and curvilinear jumps. For the relevant charge states, the barriers for diffusion range from 0.5 to 1 eV, which imply a high mobility of interstitials. Most of these properties are traced back to the defect-induced deep gap levels, their occupation, and their dependence on the defect's site. The important role of the ionicity of the host is pointed out. On the other hand, generation of Frenkel pairs on the anion sublattice requires energy of about 5 eV, and thus is nonefficient. The obtained results suggest that formation of Frenkel pairs is a microscopic origin of two effects recently observed in Schottky junctions based on CdZnTe and other II-VI alloys, namely, the reversible changes in conductivity by a few orders of magnitude, and the ferroelectric-like behavior of polarization.
机译：通过第一性原理计算研究了空位-间隙Frenkel对的形成以及CdTe，ZnTe及其合金中间隙和空位的性质。阳离子亚晶格上Frenkel对的生成在很大程度上取决于费米能量：过量自由电子的存在将使该对生成的能垒从固有样品中的2.5 eV降低到1.2 eV。此外，E_F决定了Frenkel对在重组方面的稳定性以及它们的结合能，结合能在〜0.2至〜1 eV之间变化。还发现了对于费米能量的强烈依赖性，即对电荷态的强烈依赖性，以用于稳定的位置和隔离的间隙的扩散的阻挡层。特别地，中性间隙具有两个（亚）稳定的位置，对应于两个局部的能量最小值，并通过它们之间的跳跃而扩散。带正电的插页式广告只有一个稳定的位置，并且会扩散两倍的时间，且呈曲线形跳跃。对于相关的电荷状态，扩散的势垒范围为0.5到1 eV，这意味着间隙的高迁移率。这些特性中的大多数都可以追溯到缺陷引起的深间隙水平，它们的占据以及它们对缺陷部位的依赖性。指出了主体离子化的重要作用。另一方面，在阴离子亚晶格上生成Frenkel对需要大约5 eV的能量，因此效率很低。获得的结果表明，Frenkel对的形成是最近在基于CdZnTe和其他II-VI合金的肖特基结中观察到的两种效应的微观起源，即，电导率可逆变化几个数量级，并且类似铁电体。极化行为。

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