Defects in Cu(In,Ga)Se2 Chalcopyrite Semiconductors: A Comparative Study of Material Properties, Defect States, and Photovoltaic Performance
Defects in Cu(In,Ga)Se2 Chalcopyrite Semiconductors: A Comparative Study of Material Properties, Defect States, and Photovoltaic Performance
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DOI：
10.1002/aenm.201100344
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发表时间：
2011-10-01
影响因子：
27.8
通讯作者：
Mitzi, David B.
中科院分区：
文献类型：
--
作者：
Cao, Qing;Gunawan, Oki;Mitzi, David B.
理解Cu（In，Ga）（Se，S）（2）（CIGS）中的缺陷，特别是将薄膜形成过程中的变化与材料特性、光伏（PV）器件性能和从导纳谱中提取的缺陷水平的差异相关联，是一项关键但具有挑战性的任务，这是由于这种多晶化合物半导体的复杂性质。在这里，我们提出了一个系统的比较研究，其中不同的CIGS薄膜中的缺陷密度水平是故意诱导生长CIGS颗粒使用不同的硒活性水平。通过包括X射线衍射、扫描电子显微镜、透射电子显微镜、二次离子质谱、X射线光电子能谱和中等能量离子散射的技术的材料表征结果表明，该工艺变化虽然不显著影响CIGS晶粒结构、晶体取向或本体组成，导致在CIGS表面附近的铜反位缺陷（（In，Ga）（Cu））处具有高密度铟或镓的有缺陷的黄铜矿层的增强形成，对于在硒供应不足的情况下生长的CIGS膜。该缺陷层或与其相关的膜生长条件进一步与观察到的电流-电压特性（包括翻转和交叉行为）以及在导纳谱中通常观察到的约110 meV处的缺陷状态（通常表示为N1缺陷）相关联。的（In，Ga）（Cu）缺陷对器件的PV性能的影响也成立。
Understanding defects in Cu(In,Ga)(Se,S)(2) (CIGS), especially correlating changes in the film formation process with differences in material properties, photovoltaic (PV) device performance, and defect levels extracted from admittance spectroscopy, is a critical but challenging undertaking due to the complex nature of this polycrystalline compound semiconductor. Here we present a systematic comparative study wherein varying defect density levels in CIGS films were intentionally induced by growing CIGS grains using different selenium activity levels. Material characterization results by techniques including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, secondary ion mass spectrometry, X-ray photoelectron spectroscopy, and medium energy ion scattering indicate that this process variation, although not significantly affecting CIGS grain structure, crystal orientation, or bulk composition, leads to enhanced formation of a defective chalcopyrite layer with high density of indium or gallium at copper antisite defects ((In, Ga)(Cu)) near the CIGS surface, for CIGS films grown with insufficient selenium supply. This defective layer or the film growth conditions associated with it is further linked with observed current-voltage characteristics, including rollover and crossover behavior, and a defect state at around 110 meV (generally denoted as the N1 defect) commonly observed in admittance spectroscopy. The impact of the (In, Ga)(Cu) defects on device PV performance is also established.