论文标题
II型GAAS $ _ {1-x} $ sb $ _ {x} $/gaas量子量环的电子属性
Electronic properties of type-II GaAs$_{1-x}$Sb$_{x}$/GaAs quantum rings for applications in intermediate-band solar cells
论文作者
论文摘要
我们从中间带太阳能电池（IBSCS）的应用的角度来看，我们对II型GAAS $ _ {1-x} $ sb $ _/gaas量子量环（QRS）的电子特性进行了理论分析。我们概述了Schrödinger's方程的分析解，用于无限势深度的圆柱QR，并用QR形态描述QR基态的演变。我们使用该分析模型阐明了QR的电子特性的一般方面，我们承担了多波段$ \ textbf {k} \ cdot \ cdot \ textbf {p} $计算 - 包括应变和压电效果 - 用于现实的gaas $ _ {1-x {1-X $ _ {1-x $ sb $ sb $ sb $ _ {x} x} $/我们的$ \ textbf {k} \ cdot \ textbf {p} $计算确认，gaas $ _ {1-x} $ sb $ _ {x} $ _ {x} $/gaas qrs中的大型类型-II频段偏移量很大，并进一步指示了一个位置（quasi-bound-bound-bound-bound）的位置。从IBSC设计的角度来看，计算出的电子属性表明了几个好处，包括（i）大孔电离能量，减轻中间频段的热电话发射，以及（ii）电子孔空间重叠超过那些在常规GAAS $ _ {1-X} $ _ {1-x} $ _ {x $ _ {X $ _ {x x} $ _ {X $ _ {x} $ _ {x} $ _ {x} $ _ {形态，以管理光吸收和辐射重组之间的权衡。总体而言，我们的分析从频带结构工程的角度突出了QR几何形状提供的灵活性，并确定了QR合金组成和形态的特定组合，这些组合和形态为基于QR的IBSC提供了优化的子带间隙能量。
We present a theoretical analysis of the electronic properties of type-II GaAs$_{1-x}$Sb$_{x}$/GaAs quantum rings (QRs), from the perspective of applications in intermediate band solar cells (IBSCs). We outline the analytical solution of Schrödinger's equation for a cylindrical QR of infinite potential depth, and describe the evolution of the QR ground state with QR morphology. Having used this analytical model to elucidate general aspects of the electronic properties of QRs, we undertake multi-band $\textbf{k} \cdot \textbf{p}$ calculations -- including strain and piezoelectric effects -- for realistic GaAs$_{1-x}$Sb$_{x}$/GaAs QRs. Our $\textbf{k} \cdot \textbf{p}$ calculations confirm that the large type-II band offsets in GaAs$_{1-x}$Sb$_{x}$/GaAs QRs provide strong confinement of holes, and further indicate the presence of resonant (quasi-bound) electron states which localise in the centre of the QR. From the perspective of IBSC design the calculated electronic properties demonstrate several benefits, including (i) large hole ionisation energies, mitigating thermionic emission from the intermediate band, and (ii) electron-hole spatial overlaps exceeding those in conventional GaAs$_{1-x}$Sb$_{x}$/GaAs QDs, with the potential to engineer these overlaps via the QR morphology so as to manage the trade-off between optical absorption and radiative recombination. Overall, our analysis highlights the flexibility offered by the QR geometry from the perspective of band structure engineering, and identifies specific combinations of QR alloy composition and morphology which offer optimised sub-band gap energies for QR-based IBSCs.
