Impact of Fast-Firing Conditions on Light- and Elevated-Temperature-Induced Degradation (LeTID) in Ga-Doped Cz–Si
Impact of Fast-Firing Conditions on Light- and Elevated-Temperature-Induced Degradation (LeTID) in Ga-Doped Cz–Si
复制标题
快速烧成条件对 Ga 掺杂 Cz-Si 中光致高温致退化 (LeTID) 的影响
DOI：
10.1109/jphotov.2023.3304118
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发表时间：
2023
影响因子：
3
通讯作者：
Jan Schmidt
中科院分区：
文献类型：
--
作者：
M. Winter;D. Walter;Jan Schmidt
通常在太阳能电池生产线的末端应用的快速烧制步骤触发Ga掺杂的Cz-Si晶片和由其制成的太阳能电池中的载流子寿命的“光和高温诱导的退化”（LeTID）效应。就硅块体内的缺陷形成而言，快速烧制步骤的关键参数是峰值烧制温度（<italic>FT</italic>）和传送带的带速度<italic>v</italic><sub>带</sub>，其中后者主要限定烧制峰值之后的冷却斜坡。在这篇文章中，我们表明，随着测量的<italic>FT</italic>（从680 °C到800 °C），<italic>v</italic><sub>带</sub>（从2.8到7.2 m/min）和沉积在晶片表面上的富氢氮化硅层的折射率<italic>n</italic>（从2.07到2.37）的增加，LeTID的程度和对降解过程中施加的温度的依赖性强烈增加。通过温度相关的退化实验，确定了Ga掺杂Cz-Si中LeTID机制的激活能<sub>EA</sub>=（0.55 ± 0.10）eV，该激活能与<italic>FT</italic>和<italic>v</italic><sub>带</sub>无关。<italic></italic>从这个观察，我们得出结论，一个单一的缺陷激活机制是最有可能负责检查LeTID效应，独立的射击条件。然而，浓度的复合活性缺陷中心后，LeTID关键取决于<italic>FT</italic>，<italic>V</italic><sub>带</sub>，和<italic>n</italic>，我们归因于在烧制过程中从氮化硅层的扩散氢浓度的变化。因此，我们的实验指向参与的氢在Ga掺杂的Cz-Si中观察到的LeTID机制。
The fast-firing step commonly applied at the end of solar cell production lines triggers “Light- and elevated-Temperature-Induced Degradation” (LeTID) effects of the carrier lifetime in Ga-doped Cz–Si wafers and solar cells made thereof. As far as the defect formation within the silicon bulk is concerned, the key parameters of the fast-firing step are the peak firing temperature (<italic>FT</italic>) and the band velocity <italic>v</italic><sub>band</sub> of the conveyor belt, where the latter mainly defines the cooling ramp after the firing peak. In this contribution, we show that the extent of LeTID and the dependence on the applied temperature during degradation increase strongly with increasing measured <italic>FT</italic> (from 680 °C to 800 °C), <italic>v</italic><sub>band</sub> (from 2.8 to 7.2 m/min), and the refractive index <italic>n</italic> of the hydrogen-rich silicon nitride layer deposited on the wafer surfaces (from 2.07 to 2.37). Through temperature-dependent degradation experiments, we determine an activation energy of <italic>E</italic><sub>A</sub> = (0.55 ± 0.10) eV of the LeTID mechanism in Ga-doped Cz–Si, which is independent of <italic>FT</italic> and <italic>v</italic><sub>band</sub>. From this observation we conclude that a single defect activation mechanism is most likely responsible for the examined LeTID effect, independent of the firing conditions. However, the concentration of recombination-active defect centers after LeTID depends critically on <italic>FT</italic>, <italic>v</italic><sub>band</sub>, and <italic>n</italic>, which we attribute to variations of the in-diffused hydrogen concentrations from the silicon nitride layers during firing. Our experiments hence point towards an involvement of hydrogen in the LeTID mechanism observed in Ga-doped Cz–Si.