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arXiv 1102.4977cond-mat.mes-hallcond-mat.mtrl-scicond-mat.otherphysics.comp-ph
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AlN/GaN异质结构的偏振平衡设计:在双势垒结构中的应用

Polarization-balanced design of AlN/GaN heterostructures: Application to double-barrier structures

Kristian Berland, Thorvald G Andersson, Per Hyldgaard

摘要:

反型区和耗尽区通常形成在掺杂引线(包覆层)与极性异质结构(如AlN/GAN和其他氮化物化合物)的有源区之间的界面处。耗尽区的能带弯曲形成势垒,严重阻碍垂直电子输运。这可能会破坏量子级联激光器和共振隧穿二极管等器件的性能。在这里,我们介绍了极化平衡和极化平衡设计的概念:一个结构是极化平衡时,所施加的偏置匹配的电压降所产生的自发和压电场。设计为在该偏置下工作的器件具有偏振平衡设计。这些概念提供了一个系统的方法来避免耗尽区的形成。作为一个测试案例,我们考虑的AlN/GAN双势垒结构的设计与Al $_{\tilde{x}}$ Ga $_{1-\tilde{x}}$ N引线。为了指导我们的努力,我们得出一个简单的关系所产生的极性效应,平均合金成分的有源区,和合金浓度的引线的固有电压降。极化平衡设计确保了无偏结构的基态的良好填充,而对于有效排空有源结构的偏置结构,其去除了耗尽势垒。

英文摘要:

Inversion- and depletion-regions generally form at the interfaces between doped leads (cladding layers) and the active region of polar heterostructures like AlN/GaN and other nitride compounds. The band bending in the depletion region sets up a barrier which may seriously impede perpendicular electronic transport. This may ruin the performance of devices such as quantum-cascade lasers and resonant-tunneling diodes. Here we introduce the concepts of polarization balance and polarization-balanced designs: A structure is polarization balanced when the applied bias match the voltage drop arising from spontaneous and piezeolectric fields. Devices designed to operate at this bias have polarization-balanced designs. These concepts offer a systematic approach to avoid the formation of depletion regions. As a test case, we consider the design of AlN/GaN double barrier structures with Al$_{\tilde{x}}$Ga$_{1-\tilde{x}}$N leads. To guide our efforts, we derive a simple relation between the intrinsic voltage drop arising from polar effects, average alloy composition of the active region, and the alloy concentration of the leads. Polarization-balanced designs secure good filling of the ground state for unbiased structures, while for biased structures with efficient emptying of the active structure it removes the depletion barriers.

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