Published:
2023-11-02 00:00
Source:
/ n-TOPCon 电池 B 掺杂影响 /
B扩掺杂曲线对n-TOPCon电池影响
饱和暗电流影响
接触电阻率
iVoc影响
文献报道，n+ poly-Si发射极最低复合电流密度：
~ 1.4 fA/cm2，抛光片金半接触区， 
~ 35 fA/cm2
文献报道，n+ poly-Si发射极最低复合电流密度：
B掺杂p+层发射区复合:
B掺杂发射极制备方法：
目标：降低发射极饱和暗电流密度，提升iVoc。实现方式：
变大。原因是表面复合及体复合加剧
变小。可用“传输受限发射极”（对体复合不敏感）概念解释：发射区重掺区域空穴浓度非常高，空穴寿命较低，因此空穴复合速率也较低。提升掺杂浓度，可降低金半接触区饱和暗电流密度。结深大于1.0 μm时，金半接触区饱和电流密度反而变大，主要是体复合加剧影响。SE技术综合轻扩区（钝化区）和重扩区（金半接触区域）优势
Fig. 2. ECV profiles of the change in the peak concentrations under one constant junction depth (a) Emitter D1 (d1≈0.5 μm), (b) Emitter D2 (d2≈0.63 μm), (c) Emitter D3 (d3≈0.8 μm); the change in junction depths under one constant peak concentration (d) Emitter N1(N1≈3E19 atoms/cm3 ) and (e) Emitter N2 (N2≈ 2.6E19 atoms/cm3 ).
Fig. 3. Emitter dark saturation current densities in the passivated regions of (a) emitter D1, (b) emitter D2, (c) emitter D3, (d) emitter N1 and (e) emitter N2. And (f)the J0e, passivated as a function of the junction depth and the peak concentration of B-doped profile.
Fig. 4. The photograph of the screen-printing pattern of the sample with different metallization fraction from 2% to 8% (a) and Photoluminescence (PL) image (b) of the symmetrical samples were boron-diffused and passivated by Al2O3/SiNx films with our different metallization fractions on the front side. The metal was etched away before the PL measurement. The numbers in percentage indicate the metallization fractions.
Fig. 5. The plots of emitter dark saturation current densities in the passivation on the contact regions of (a) emitter D1, (b) emitter D2, (c) emitter D3, (d) emitter N1, (e) emitter N2 and (f) the 3D-plot of J0e, metal as a function of the junction depth and the peak concentration of B-doped profile.
以上时，会显著增加金半接触区复合。表明在深度0.63 μm处B掺杂浓度临界点要低于E18量级
Fig. 6. (a) Scanning electron microscopy (SEM) image of emitter D3 sample (1.94 × 1019 atoms/cm3 ) surface after etching away the Ag–Al contact, the glass layer, the passivation layer, and all spikes. Remaining spikes imprints in red circles; (b)/(c) SEM cross section of contact spot. The shape of a corroded pyramid can be clearly seen.
Fig. 8. iVoc and Lifetime of the precursor structure wafers obtained from (a) emitter D1, (b) emitter D2, (c) emitter D3, (d) emitter N1 and (e) emitter N2.
Fig. S1 Measured total J0 vs. the metallization fraction f of the symmetrically the p+np+ samples for the extraction of J0 at the contact regions.
Yablonovitch极限电流密度 46.43 mA/cm2
三种电流损失
蓝光损失
基体收集损失
不均匀导致的损失，硅片片内质量不均匀导致的电流损失
复合导致的电流损失
结深越深，蓝光损失越高
Fig. 10. The curve for internal quantum efficiency (IQE) and the dashed line curve for optical reflection for (a) emitter D1, (b) emitter D2, (c) emitter D3, (d) emitter N1 and (e) emitter N2.
Fig. 11. Current loss mechanisms for (a) emitter D1, (b) emitter D2, (c) emitter D3, (d) emitter N1 and (e) emitter N2.
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