Viability of intermediate band solar cells based on InAs/GaAs submonolayer quantum dots and the role of surface reconstruction
Viability of intermediate band solar cells based on InAs/GaAs submonolayer quantum dots and the role of surface reconstruction
复制标题
基于 InAs/GaAs 亚单层量子点的中带太阳能电池的可行性以及表面重构的作用
DOI：
10.1016/j.solmat.2023.112281
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发表时间：
2023
影响因子：
6.9
通讯作者：
Quivy, A.A.
中科院分区：
文献类型：
--
作者：
Borrely, T.;Alzeidan, A.;de Lima, M.D.;Jacobsen, G.M.;Huang, T.-Y.;Yang, Y.-C.;Cantalice, T.F.;Goldman, R.S.;Teodoro, M.D.;Quivy, A.A.
生长条件对 InAs/GaAs 亚单层量子点太阳能电池的影响仍然是一个很少被探索的话题，文献显示了关于这些器件效率的相互矛盾的结果。通过电学和光学表征（光致发光、电流-电压曲线和外部量子效率）和有效质量近似中的自洽薛定谔-泊松模拟，我们研究了在沉积 InAs/GaAs 亚单层量子点之前重建 GaAs(001) 表面如何影响这些纳米结构的特性和太阳能电池的性能。电流-电压特性和外量子效率曲线表明，使用 (2 × 4) 表面重构代替常用的 c(4 × 4) 表面重构可以带来更高的短路电流密度并改善室温下的性能。与 c(4 × 4) 表面重建相比，(2 × 4) 表面重建还导致低温下光致发光强度增强。这些模拟基于之前 InAs/GaAs 亚单层量子点的横截面扫描隧道显微镜数据，表明这两种类型的亚单层量子点都无法限制电子，因为它们太小且 In 含量太低。然而，电子基态更接近于被限制在通过 (2 × 4) 表面重建生长的 SMLQD 中，因为这种纳米结构被厚的 InGaAs 层包围，其 In 含量比其他表面重建的要低。本文提出的讨论阐明了文献中关于 InAs/GaAs 亚单层量子点太阳能电池转换效率的不同报告之间的矛盾，并指出了在这些器件中实现 3D 电子限制的可能方法。
The effects of growth conditions on InAs/GaAs submonolayer-quantum-dot solar cells are still a little explored topic, and the literature shows contradictory results regarding the efficiency of these devices. Through electrical and optical characterizations (photoluminescence, current-voltage curves, and external quantum efficiency) and self-consistent Schrödinger–Poisson simulations in the effective-mass approximation, we investigate how the reconstruction of the GaAs(001) surface prior to the deposition of InAs/GaAs submonolayer quantum dots influences the properties of these nanostructures and the performance of solar cells. Current-voltage characteristics and external quantum efficiency curves show that the use of the (2 × 4) surface reconstruction—instead of the commonly used c(4 × 4) surface reconstruction—leads to higher short-circuit current density and improved performance at room temperature. The (2 × 4) surface reconstruction also leads to enhanced photoluminescence intensity at low temperatures compared to the c(4 × 4) surface reconstruction. The simulations—which are based on previous cross-sectional scanning tunneling microscopy data of InAs/GaAs submonolayer quantum dots—indicate that neither type of submonolayer quantum dot can confine electrons, as they are too small and their In content is too low. However, the electron ground state is closer to being confined in the SMLQDs grown with the (2 × 4) surface reconstruction, as such nanostructures are surrounded by a thick InGaAs layer having a lower In content than for the other surface reconstruction. The discussion presented herein elucidates a contradiction between different reports found in the literature regarding the conversion efficiency of InAs/GaAs submonolayer-quantum-dot solar cells and indicates possible ways forward for achieving 3D electron confinement in these devices.