Relation Between Resistance Drift and Optical Gap in Phase Change Materials,Advanced Theory and Simulations

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Relation Between Resistance Drift and Optical Gap in Phase Change Materials
Advanced Theory and Simulations ( IF 2.9 ) Pub Date : 2020-09-07 , DOI: 10.1002/adts.202000117
Jose C. Martinez ₁ , Robert E. Simpson ₁

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The optical contrast in a phase change material is concomitant with its structural transition. These two are connected by first recognizing that Friedel oscillations couple electrons propagating in opposite directions and supply an additional Coulomb energy. As the crystal switches phase, this energy acquires time dependence and the Landau‐Zener mechanism operates, steering population transfer from the valence to the conduction band and vice versa. Spectroscopy suggests that the oscillator energy E₀ dominates the optical properties and a calculation involving the crystalline field and spin–orbit interaction yields good estimates for E₀ of both structural phases. Further analysis relates the optical gap with the crystalline‐field energy as well as activation energy for electrical conduction. This last property characterizes the amorphous phase, thereby furnishing a link between the crystalline field and the activation energy and ultimately with the resistance drift exponent. Providing optical means to quantify resistance drift in phase‐change materials (PCMs) could circumvent the need for fabricating expensive devices and performing time consuming measurements.

中文翻译：

相变材料中的电阻漂移与光学间隙之间的关系

相变材料中的光学对比度与其结构转变同时发生。通过首先认识到弗里德尔振荡耦合了沿相反方向传播的电子并提供了额外的库仑能量，从而将这两者联系起来。当晶体切换相时，该能量获得时间依赖性，并且Landau-Zener机制开始工作，控制总体从价态向导带的转移，反之亦然。光谱学表明，振荡器能量E ₀占主导地位的光学特性，并且涉及晶体场和自旋轨道相互作用的计算得出了对E _0的良好估计两个结构阶段。进一步的分析将光隙与晶体场能量以及用于电导通的活化能相关。该最后的特性表征了非晶相，从而提供了结晶场与活化能之间的联系，并最终提供了电阻漂移指数。提供光学手段来量化相变材料（PCM）中的电阻漂移可能会避免制造昂贵的设备和执行耗时的测量的需求。

更新日期：2020-10-05

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