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Silicon solar cell metallisation with chemically sculptured surface - uses metallisation of contacts post surface doping as mask for chemical etch to remove surface traps and reduce absorption in face layer
Silicon solar cell metallisation with chemically sculptured surface - uses metallisation of contacts post surface doping as mask for chemical etch to remove surface traps and reduce absorption in face layer
The photocell consists of a plane substrate with an active surface layer (11) of opposite types of conductivity through which the cell is irradiated and the active region (5) lies at the boundary between this layer and the substrate. The cell is covered with a network of conductors over the surface layer which is of uniform thickness. The surface layer is then chemically etched to reduce its thickness between the conductors (111) which act as a protective mask. The silicon substrate is cut parallel to the (111) plane of the crystal and in the case of a back surface field cell the front and rear faces are doped by vapour phase diffusion simultaneously with phosphine and boron hydride, the boron diffusing more slowly. A triple metallisation using fine titanium and palladium powder followed by coarser silver powder. The cell is etched using a 10 to 30 percent by volume aq. soln. of KOH at 80 to 100 deg. C for 2 to 3 minutes. The surface layer is reduced to 0.5 pm and about 90 Ohms per square resistance with only a slight undercut of the metallisation. The edges of the cell are deeply etched completely eroding the surface region (13) and surface traps.
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机译：光电管由一个平面基板组成，该基板具有相反类型的导电性的活性表面层（11），通过该表面可照射该单元，并且有源区域（5）位于该层和基板之间的边界处。电池在表面层上覆盖有厚度均匀的导体网络。然后化学蚀刻该表面层以减小其在用作保护掩模的导体（111）之间的厚度。平行于晶体的（111）平面切割硅衬底，在背面场电池的情况下，正面和背面通过气相扩散与磷化氢和氢化硼同时掺杂，硼扩散速度更慢。使用精细的钛和钯粉末进行三重金属化，然后使用较粗的银粉末。用10至30体积％的水溶液蚀刻电池。 soln。 80至100度的KOH C 2至3分钟。该表面层降低到0.5 pm，每平方电阻约90欧姆，而金属化作用仅略有底切。电池的边缘被深蚀刻，完全腐蚀了表面区域（13）和表面陷阱。
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