【摘要】 结合多层结构模型以及柯西色散公式,给出一种由透射谱提取微晶硅锗(μc-Si1-x Gex:H)薄膜光学常数的Matlab方法。与Swanepeol方法、PUMA(pointwise unconstrained minimization approach)方法相比,Matlab法通过透射率极值的位置而非幅值计算折射率,能够避免幅值大小偏差所造成的影响,得到更准确的光学常数,拟合精度能提高1个数量级。计算所得不同Ge含量的光学常数表明,μc-Si1-x Gex:H在整个波长范围内有更高的吸收系数和折射率,并且二者随Ge含量增加而增加。由ASA(advanced semiconductor analysis)进一步计算表明,相对于μc-Si:H电池,当本征吸收层较薄时相同厚度的μc-Si1-x Gex:H电池从400nm开始即能表现出更高的量子效率(QE)响应,当本征吸收层较厚时相同厚度的μc-Si1-x Gex:H电池在近红外区域的QE响应依然优势明显。并且,在获得相同电流密度的情况下,μc-Si1-x Gex:H电池能够明显降低本征吸收层厚度,因而能够有效降低Si基薄膜太阳电池的制造成本。更多还原

【Abstract】 In this paper,we study the optical constants of hydrogenated microcrystalline silicon germanium alloy(μc-Si1-x Gex:H)fabricated by plasma enhanced chemical vapor deposition(PECVD).First we propose a Matlab method to abstract optical constants from the transmission spectra,which is based on multi-layer model and the Cauchy dispersion formula.Compared with traditional fringe pattern methods,such as Swanepeol method,pointwise unconstrained minimization approach(PUMA),the Matlab method determines the refractive index not from the amplitude of the interference fringe but from the position of the interference fringe,so it can avoid the negative influence owing to the deviation of the amplitude and can offer more precise optical constants,and it can enhance the fitting precision by one order of magnitude.The results show that the absorption coefficients and the refractive indices ofμc-Si1-x Gex:H are higher than those ofμc-Si:H in the whole spectrum,and increase as the Ge content increases.The further results calculated by advanced semiconductor analysis(ASA)demonstrate that compared withμcSi:H,μc-Si1-x Gex:H PIN solar cells with the same thickness present higher quantum efficiency(QE)response from 400nm when the absorber is thin,and can also achieve higher QE response in the near-in-frared region when the absorber is thick.On the other hand,to realize the same current density,μc-Si1-x Gex :H can reduce the thickness effectively,so it can reduce the fabricating cost of thin film solar cells apparently.更多还原