用于GaAs上1550 nm光伏转换器的AlGaInAs组分渐变缓冲层中相分离的抑制
Suppression of Phase Separation in AlGaInAs Compositionally Graded Buffers for 1550 nm Photovoltaic Converters on GaAs
AI总结：
本研究通过高失配角衬底和Zn掺杂抑制AlGaInAs渐变缓冲层中的相分离，降低穿透位错密度，实现了0.74 eV GaInAs器件在1570 nm激光下31.9%的峰值转换效率，为规模化应用提供路线图。
摘要：
我们研究了在跨越从GaAs到InP晶格常数范围的AlGaInAs组分渐变缓冲层（CGBs）中抑制相分离并降低穿透位错密度（TDD）的策略。结合高分辨率X射线衍射、阴极发光、透射电子显微镜和光伏器件测量的结果，我们将外延生长条件的选择与CGBs的缺陷结构及后续器件性能相关联。研究表明，使用相对于(100)面向(111)A面高失配角度的衬底以及采用Zn掺杂而非Si掺杂，均能抑制相分离并降低TDD。我们展示了一个在(411)A GaAs衬底上使用Zn掺杂AlGaInAs CGB生长的0.74 eV GaInAs器件，其TDD为3.5 ± 0.2 x 10^6 cm^-2，在AM1.5G太阳光谱下测得的带隙-开路电压偏移仅为0.434 V。我们在1570 nm激光的高强度辐照下对该器件进行了表征，并在3.6 W/cm^2下测得了31.9%的峰值效率激光功率转换效率。这些结果为制造激光和热功率转换器件提供了路线图，其性能和成本效益足以推动这些技术的大规模应用。
英文摘要：
We investigate strategies to suppress phase separation and reduce threading dislocation densities (TDD) in AlGaInAs compositionally graded buffers (CGBs) that span the lattice constant range from GaAs to InP. Combining results from high resolution x-ray diffraction, cathodoluminescence, transmission electron microscopy, and photovoltaic device measurements, we correlate choices of epitaxial growth conditions with the defect structure of the CGBs and subsequent device performance. Both the use of substrates with high misorientation off (100) towards the (111)A plane and Zn-doping instead of Si-doping are shown to suppress phase separation and reduce TDD. We demonstrate a 0.74 eV GaInAs device grown on a (411)A GaAs substrate using a Zn-doped AlGaInAs CGB with TDD = 3.5 +/- 0.2 x 106 cm^-2 that has a bandgap-open circuit voltage offset of only 0.434 V measured under the AM1.5G solar spectrum. We characterized this device under high-intensity irradiance from a 1570 nm laser and measured a 31.9% peak efficiency laser power conversion efficiency at 3.6 W/cm2. These results provide a roadmap to the manufacture of laser- and thermal-power conversion devices with the performance and cost-effectiveness needed to drive adoption of these technologies at scale.
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