GaAs thermophotovoltaic patterned dielectric back contact devices with improved sub-bandgap reflectance
GaAs thermophotovoltaic patterned dielectric back contact devices with improved sub-bandgap reflectance
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DOI：
10.1016/j.solmat.2021.111545
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发表时间：
2022-02-03
影响因子：
6.9
通讯作者：
King, Richard R.
中科院分区：
文献类型：
--
作者：
Arulanandam, Madhan K.;Steiner, Myles A.;King, Richard R.
我们展示了具有图图化介电背触点（PDBC）结构的砷化镓热光伏（TPV）器件，其特点是在大部分背表面的半导体和背金属触点之间有一个介电间隔，具有高反射率，并且在较小的区域上有金属点触点，用于导电。在TPV应用中，需要高的亚带隙反射率来将未使用的亚带隙光子反射到热发射器，以尽量减少热光谱中这部分的能量损失。我们探索了使用SU-8和SiO2介电间隔层制备PDBC的不同工艺，以最大限度地提高亚带隙反射率，同时最小化串联电阻，从而提高TPV转换效率。我们成功地演示了GaAs SU-8 PDBC TPV器件，其2200℃黑体加权子带隙反射率分别为94.9%和96.5%，有和没有前金属栅格。这比GaAs基线TPV器件的平均子带隙反射率（94.2%）高出0.7%和2.3%（绝对）。具有前栅格的TPV器件较低的亚带隙反射率表明，前栅格诱导光散射导致TPV器件中额外的寄生吸收。我们还表明，对于较高的接触覆盖分数，PDBC反射率通常不能用简单的一维传递矩阵方法建模的线性插值来处理，而应该通过求解三维麦克斯韦方程组来处理衍射光栅。
We demonstrate GaAs thermophotovoltaic (TPV) devices with a patterned dielectric back contact (PDBC) architecture, featuring a dielectric spacer between the semiconductor and back metal contact over most of the back surface for high reflectance, and metal point contacts over a smaller area for electrical conduction. In the TPV application, high sub-bandgap reflectance is needed to reflect unused sub-bandgap photons to the thermal emitter to minimize energy losses in this portion of the thermal spectrum. We explore different PDBC fabrication processes with SU-8 and SiO2 dielectric spacer layers to maximize sub-bandgap reflectance while minimizing series resistance to increase TPV conversion efficiency. We successfully demonstrate GaAs SU-8 PDBC TPV devices with 2200 degrees C blackbody-weighted sub-bandgap reflectance of 94.9% and 96.5% with and without a front metal grid, respectively. This is 0.7% and 2.3% (absolute) higher than the mean sub-bandgap reflectance of 94.2% for GaAs baseline TPV devices with 100% Au back contact with front metal grid. Lower sub-bandgap reflectance in TPV devices with front grids indicates the front grid induces light scattering leading to additional parasitic absorption in the TPV device. We also show that for higher contact coverage fractions, the PDBC reflectance cannot in general be treated by a linear interpolation using simple 1D transfer matrix method modeling and should be treated instead as a diffraction grating by solving Maxwell's equations in 3D.