[论文解读] Mid-Infrared Thermal Radiation Harvesting using Uncooled Narrow Bandgap GeSn Thermophotovoltaic cell

Gérard Daligou, Mahmoud R. M. Atalla+5 more|arXiv (Cornell University)|Feb 24, 2026

Thermal Radiation and Cooling Technologies被引用 0

一句话总结

论文展示了在硅基上实现的 GeSn p-i-n TPV 二极管的概念验证，具有可测的响应度和输出，并提供了材料质量改进后潜在的本征性能显著提升的建模分析。

ABSTRACT

Thermophotovoltaic (TPV) cells are increasingly attractive for applications in industrial waste heat harvesting, aerospace energy management, and compact power generation. Deploying midwave-infrared (MWIR) TPV in practical applications requires narrow-bandgap semiconductors that not only absorb low-energy photons but also integrate with scalable, low-cost platforms. Although high-performance TPV devices have been demonstrated using III-V materials such as InAs, GaSb, and InGaAs(P), their use remains limited by cost and substrate size. With this perspective, narrow bandgap GeSn alloys are a promising alternative that extend group-IV absorption into the MWIR while being silicon-compatible. Although the potential of GeSn TPV cells has been predicted, no experimental demonstration has been reported. Here, proof-of-concept Ge$_{0.91}$Sn$_{0.09}$ p-i-n TPV diodes (1 mm diameter) grown on silicon were fabricated and their performance was benchmarked against commercial InAs and extended-InGaAs devices. Measurements at 300 K under 2.33 $μ$m laser and $\sim$1500 K SiC Globar illumination revealed peak responsivity of $\sim$ 0.2 A/W at $\sim$ 1.7 $μ$m, and an output power of $\sim$ 0.41 mW/cm$^2$. These devices show trends comparable to those of the InAs diode under identical conditions, although at reduced absolute levels. To assess the intrinsic performance potential, Poisson-drift-diffusion modeling incorporating experimentally calibrated emitter emissivity predicts power densities exceeding 1 W/cm$^2$ under moderate MWIR thermal illumination, indicating that the present devices operate far below their fundamental limits and are primarily constrained by defect-assisted recombination and transport losses. These results establish GeSn as a scalable, silicon-compatible MWIR TPV platform and highlight a larger performance potential achievable through material and device optimization.

研究动机与目标

• 将 GeSn 作为与硅兼容的、用于热光伏（TPV）的 MWIR 吸收材料进行动机阐述。
• 在硅上生长 GeSn p-i-n TPV 二极管并在受控照明条件下与 InAs 和扩展 InGaAs 探测器进行基准比较。
• 通过结合发射体发射率的器件尺度泊松-漂移扩散建模来评估本征性能潜力。
• 识别材料/缺陷限制（复合、传输）对当前 TPV 设备的约束，并勾勒改进路径。

提出的方法

• 通过 RPCVD，在 4 寸硅(100) 基底上使用 Ge 虚拟衬底生长 GeSn p-i-n 异质结构。
• 制作圆形 mesa 垂直 p-i-n 器件（直径 1 mm），进行钝化及 Ti/Au/Ag/Au 电极接触。
• 在暗态、2.3 μm 激光及宽带 SiC Globar 照明条件下表征光谱响应度和 I-V 特性。
• 利用傅立叶变换红外光谱（FTIR）测量将光谱响应度与 InAs 探测器进行标定。
• 开发一维泊松-漂移扩散模拟，并耦合光学生成（通过传输矩阵法）以估算上限性能。

Figure 1 : Ge 0.94 Sn 0.06 /Ge 0.91 Sn 0.09 /Ge 0.95 Sn 0.05 $p$ - $i$ - $n$ device structure and SiC-based illumination setup. (a) Schematic and optical micrograph of a representative $p$ - $i$ - $n$ TPV device. The glossy-like material covering the device represents the SiO 2 passivation layer, wh

实验结果

研究问题

• RQ1 在现实 TPV 照明条件下，生长在硅上的 GeSn p-i-n TPV 二极管是否能实现 MWIR 光响应以及可测量的功率转换？
• RQ2 在相同几何条件下，与商用 InAs 和扩展 InGaAs 器件相比，GeSn 的性能如何？
• RQ3 当非辐射和传输损耗被最小化时，GeSn TPV 器件的本征性能潜力有多大？
• RQ4 限制 GeSn TPV 性能的主导损耗机制是什么，它们如何随材料质量改进而改变？

主要发现

• GeSn p-i-n TPV 二极管在约 1.7–2.1 μm 之间的峰值响应度约为 0.2 A/W。
• 在 2.3 μm 激光照明下，I_sc 约为 0.353 mA，V_oc 约为 24 mV，输出功率密度约为 0.27 mW/cm2（归一化）。
• 在宽带约 1500 °C 的 SiC 发射源照明下，GeSn 设备实现约 0.41 mW/cm2 的输出功率密度，仍低于 InAs 和扩展 InGaAs 的性能。
• 1D 泊松-漂移扩散仿真预测在中等 MWIR 热照明下功率密度可超过 1 mW/cm2，表明当前器件受缺陷、传输和接触限制。
• 仿真显示 SRH 复合与缺陷密度主导电压和电流损失，提示材料质量改进有潜在的性能提升。
• 该研究验证 GeSn 作为可扩展、与硅兼容的 MWIR TPV 平台，并指出在材料与器件优化后存在显著的本征性能裕度。

Figure 2 : Broadband source characterization and dark I-V device characteristics. (a) Emission spectrum of the SiC heating element at \qty ∼1500, highlighting its broadband gray-body distribution extending across the mid-infrared thorlabsSiC . (b) I-V characteristics under dark condition for devices