Recently recorded efficiencies of Cu(In,Ga)Se₂ based solar cells were mainly achieved by surface treatment of the absorber that modifies the buffer–absorber interface region. However, only little is known about the electronic properties within this region. In this manuscript voltage dependent admittance spectroscopy is applied to low temperature grown Cu(In,Ga)Se₂ based solar cells to detect near interface defect states in the absorber. Under non-equilibrium conditions even defect states close to the interface may cross the Fermi level and hence are detectable using capacitance based measurement methods, in contrast to the case of zero bias conditions. Such defects are of potential importance for understanding device limitations and hence, adequate characterization is necessary. A SCAPS model is developed including a near interface deep acceptor state, which explains the frequency and voltage dependence of the capacitance. Using the same model, also the experimental apparent doping density is explained.

中文翻译：

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电压相关导纳光谱技术，用于检测薄膜太阳能电池的近界面缺陷状态

最近记录的基于Cu（In，Ga）Se ₂的太阳能电池的效率主要是通过对吸收剂进行表面处理来实现的，该表面处理剂修改了缓冲-吸收剂的界面区域。但是，对该区域内的电子特性知之甚少。在此手稿中，电压依赖性导纳光谱技术适用于低温生长的Cu（In，Ga）Se ₂太阳能电池来检测吸收体中的近界面缺陷状态。在非平衡条件下，甚至接近界面的缺陷状态也可能会越过费米能级，因此与零偏置条件下的情况相比，可以使用基于电容的测量方法来检测。这些缺陷对于理解器件的局限性具有潜在的重要性，因此，有必要进行充分的表征。开发了包括附近界面深受体状态的SCAPS模型，该模型解释了电容的频率和电压依赖性。使用相同的模型，还解释了实验表观掺杂密度。