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首页> 外文期刊>Physical review >Using Superlattice Ordering To Reduce The Band Gap Of Random (in,ga)as/inp Alloys To A Target Value Via The Inverse Band Structure Approach
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Using Superlattice Ordering To Reduce The Band Gap Of Random (in,ga)as/inp Alloys To A Target Value Via The Inverse Band Structure Approach

机译：使用超晶格排序通过逆能带结构方法将无定形（in，ga）as / inp合金的能带隙减小到目标值

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摘要

Thermophotovoltaic (TPV) devices are intended to absorb photons from hot blackbody radiating objects, often requiring semiconductor absorbers with band gap of approx=0.6 eV. The random In_xGa_(1-x)As alloy lattice matched (x_(In)=0.53) to a (001) InP substrate has a low-temperature band gap of 0.8 eV, about 0.2 eV too high for a TPV absorber. Bringing the band gap down by raising the In concentration induces strain with the substrate, leading to a two-dimensional (2D) → three-dimensional (3D) morphological transition occurring before band gaps suitable for TPV applications are achieved. We use the inverse band structure approach, based on a genetic algorithm and empirical pseudopotential calculations, to search for lattice-matched InAs/GaAs multiple-repeat unit structures with individual layer thicknesses lower than the critical thickness for a 2D→3D transition. Despite the fact that quantum confinement usually increases band gaps, we find a quantum superlattice structure with the required reduced gap (and a significant optical transition) that matches all target requirements. This is explained by the predominance of (potential-energy) level anticrossing effects over (kinetic) quantum confinement effects.
机译：热光电（TPV）器件旨在吸收来自热黑体辐射物体的光子，通常需要带隙约为0.6 eV的半导体吸收体。与（001）InP衬底匹配（x_（In）= 0.53）的无规In_xGa_（1-x）As合金晶格具有0.8 eV的低温带隙，对于TPV吸收剂而言，该温度带隙太高约0.2 eV。通过提高In浓度来降低带隙会引起基板应变，从而导致在实现适合TPV应用的带隙之前发生二维（2D）→三维（3D）形态转变。我们使用基于遗传算法和经验伪势能计算的逆带结构方法，搜索晶格匹配的InAs / GaAs多重复单元结构，其单个层厚度低于2D→3D过渡的临界厚度。尽管事实上量子限制通常会增加带隙，但我们发现了一种量子超晶格结构，其所需要的缝隙减小了（并且发生了明显的光学跃迁），可以满足所有目标要求。这可以通过（势能）能级反交叉效应相对于（动力学）量子约束效应的优势来解释。

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