Exponential size-dependent tunability of strain on the transport behavior in ZnO tunnel junctions: an ab initio study
Exponential size-dependent tunability of strain on the transport behavior in ZnO tunnel junctions: an ab initio study
复制标题
ZnO 隧道结输运行为的应变指数尺寸依赖性可调性：从头算研究
DOI：
10.1039/c5cp03945b
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发表时间：
2015
影响因子：
3.3
通讯作者：
Zheng Yue
中科院分区：
文献类型：
--
作者：
Zhu Jia;Chen W. J.;Zhang G. H.;Zheng Yue
压电隧道结的输运行为是否对外部应变或应力敏感是一个有趣的问题，这意味着开发新型机械传感器、换能器、压电器件等的前景。许多研究关注这一问题，但隧道结的应变和应力可调输运行为如何依赖于势垒厚度仍然很少有人知道。利用第一性原理计算，我们研究了隧道结中的尺寸依赖和应变可调的输运行为。结果表明，外加应变对ZnO隧道结的输运性质有很强的控制作用，应变反转可使隧道电导放大数倍。更重要的是，应变反转的电导放大随势垒厚度呈指数变化，表明输运行为的尺寸依赖的应变可调谐性。静电量（即，内建场、退极化场、极化、界面偶极子和势垒）和隧道结的输运性质进行了综合分析，揭示了这些量与尺寸依赖性之间的关系。ZnO隧道结中应变可调输运行为的指数尺寸依赖性归因于势垒随势垒厚度的线性变化。我们的模拟提供了一个洞察如何最大限度地提高应变可调性的压电隧道结的厚度设计和应变工程的输运行为。
It is an interesting issue if the transport behavior of a piezoelectric tunnel junction is sensitive to external strain or stress, and it implies a prospect for developing novel mechanical sensors, transducers, piezotronic devices, etc. Many studies paid attention to this issue, yet how the strain and stress tunable transport behavior of a tunnel junction depends on the barrier thickness is still rarely known. Using the first principles calculations, we investigate the size-dependent and strain-tunable transport behavior in the tunnel junctions. It was confirmed that external strain has strong control over the transport properties of ZnO tunnel junctions, with several times amplification of tunnel conductance obtained by strain reversal. More importantly, the conductance amplification by strain reversal exponentially changes with the barrier thickness, indicating the size-dependent strain tunability of the transport behavior. The electrostatic quantities (i.e., built-in field, depolarization field, polarization, interfacial dipoles and potential barrier) and the transport properties of tunnel junctions were comprehensively analyzed to reveal the relationships between these quantities and their size dependence. The exponential size-dependence of strain tunable transport behavior in ZnO tunnel junctions is attributed to the linear change in the potential barrier with the barrier thickness. Our simulations provide an insight of how to maximize the strain tunability of transport behavior of piezoelectric tunnel junctions by thickness design and strain engineering.