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arXiv 1208.5849cond-mat.mtrl-sciphysics.comp-phquant-ph
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高效率UV发射极--GaN/AlN异质结构的理论研究

High efficiency UV emitters - theoretical investigation of GaN/AlN heterostructures

Pawel Strak, Pawel Kempisty, Stanislaw Krukowski

摘要:

采用密度泛函理论模拟了GAN/AlN体系的物理性质。将这两种化合物结合到多量子阱(MQW)结构中将诱导强静电效应,导致在AlN/GAN界面处出现高量级偶极层,这首先由{Tersoff Phys.Rev.B30(8)pp.4874(1984)}假设,并且已经由{Romanowski et al.J.Phys.Chem.C114}在GAN/InN中确定。14410(2010)}。当结合GAN和AlN的异质结构中的波函数的空间投影表明,状态之间的价带偏移成为的顺序为0.85 V的系统分析的影响的数量的Ga原子层上的性质的井已经表明,对于厚度高达4 Ga层,GAN表现为载流子定位潜在的最小值,而对于更大的厚度,它是一个标准的量子阱。在所有情况下,阱具有接近价带最大值(VBM)和导带最小值(CBM)的强局域化量子态。计算的振荡器强度值对于超过8 Ga层(~21 μ m)的阱厚度迅速减小,这表明用于UV发射器的阱应该比基于InGaN/GAN系统的阱薄得多。量子限制斯塔克效应(QCSE)相关的跃迁能量的变化的函数的几何排列也得到了。

英文摘要:

Density functional theory simulations were used to obtain physical properties of GaN/AlN system. Combination of these two compounds into multiquantum well (MQW) structure will induce strong electrostatic effect leading to emergence of high magnitude dipole layers at the AlN/GaN interfaces, which were first postulated by {Tersoff Phys. Rev. B 30(8) pp.4874 (1984)} and already identified in GaN/InN by {Romanowski et al. J. Phys. Chem C 114. 14410 (2010)}. When combining GaN and AlN in to a heterostructure a spatial projection of wavefunctions indicate that valence band offset between states becomes of order of 0.85 V. Systematic analysis of influence of number of Ga atomic layers on the properties of wells have shown that for thickness up to 4 Ga layers, GaN behave as carriers locating potential minimum rather, while for larger thickness it is a standard quantum well. In all cases wells has strongly localized quantum states close to valance band maxima (VBM) and conduction band minimum (CBM). The calculated oscillator strength values rapidly decreases for the well thickness in excess of 8 Ga layers (~21 Å) which indicates that wells for UV emitters should be much thinner than these based on InGaN/GaN systems. The Quantum Confined Stark Effect (QCSE) related changes of the transition energy in function of the geometric arrangement were also obtained.

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