钝化
材料科学
硅
蚀刻(微加工)
带隙
图层(电子)
非晶硅
载流子寿命
无定形固体
光电子学
纳米
晶体硅
复合材料
结晶学
化学
作者
Dimitrios Deligiannis,Vasileios Marioleas,Ravi Vasudevan,C.C.G. Visser,R.A.C.M.M. van Swaaij,Miro Zeman
摘要
This work studies the dependency of the effective lifetime on the a-Si:H layer thickness of c-Si substrates passivated with intrinsic a-Si:H. This is experimentally investigated by using a soft wet-etching method that enables accurate control of the a-Si:H layer thickness. In this way, variations in the effective lifetime down to thicknesses of a few nanometers are studied, while excluding effects originating from the deposition conditions of a-Si:H when samples of different thicknesses are fabricated. For thin passivation layers, results show a strong thickness dependency of the effective lifetime, which is mainly influenced by the recombination at the external a-Si:H surfaces. For thicker passivation layers, the effective lifetime is predominantly determined by the bulk a-Si:H and/or c-Si defect density. During the etching of the a-Si:H passivation layers, a gradient in the Cody gap for our samples is observed. This gradient is accompanied by a stronger decrease in the effective lifetime and is attributed to a decrease in the a-Si:H band gap and valence band offset. The observed changes in lifetime with a-Si:H layer thickness are supported with AFORS-HET simulations. When a gradient in the a-Si:H passivation layer band gap is used, simulations can reproduce the experimental results.
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