The electronic structure of Cu(In1-xGax)Se2 alloyed with silver
The electronic structure of Cu(In1-xGax)Se2 alloyed with silver
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DOI：
10.1016/j.tsf.2011.01.368
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发表时间：
2011-08-31
期刊：
影响因子：
2.1
通讯作者：
Cohen, J. David
中科院分区：
文献类型：
--
作者：
Erslev, Peter T.;Lee, JinWoo;Cohen, J. David
我们研究了（Ag 1-xCux）（In 1-yGay）Se-2（ACIGS）合金在宽范围的组成上的电子性质，以评估与Cu（In 1-yGay）Se-2（CIGS）合金相比，这种合金是否可以允许在更大的带隙处实现更大的V-OC值。我们的研究采用了结电容技术，如驱动电平电容分布（DLCP）和瞬态光电容（TPC）光谱，以及温度依赖的J-V测量。TPC光谱不仅揭示了带隙确实随着Ag分数的增加而增加，而且所有ACIGS样品中的带尾（或Urbach能量）基本上小于相应带隙的CIGS样品。这表明Ag合金化以某种方式降低了存在的无序程度。DLCP测量表明自由载流子密度非常低，约为10（14）cm（-3），以及位于CdS/ACIGS结处的缺陷的证据。随温度变化的I-V测量揭示了一个明显的“扭结”的V-OC与T的特性，表明从界面陷阱限制制度的批量限制制度的过渡。温度低于250 K.当样品被光浸泡时，V-OC增加高达0.1V。这表明限制V-OC的界面陷阱可以通过暴露于光而钝化。(C)2011 Elsevier B. V.保留所有权利。
We have examined the electronic properties of (Ag1-xCux)(In1-yGay)Se-2 (ACIGS) alloys over a wide range of compositions to assess whether such alloys might allow one to achieve larger values of V-OC at larger band gaps compared to the Cu(In1-yGay)Se-2 (CIGS) alloys. Our studies employed junction capacitance techniques such as drive level capacitance profiling (DLCP) and transient photocapacitance (TPC) spectroscopy, as well as temperature dependent J-V measurements. The TPC spectra revealed not only that the band gap did indeed increase as the Ag-fraction was increased, but also that the bandtailing (or Urbach energies) in all ACIGS samples were substantially smaller than for CIGS samples of corresponding band gaps. This indicates that the Ag alloying somehow reduces the degree of disorder present. The DLCP measurements indicated very low free carrier densities, on the order of 10(14) cm(-3), as well as evidence of defects located at the CdS/ACIGS junction. Temperature-dependent I-V measurements revealed a distinct "kink" in the V-OC vs T characteristics, suggesting a transition from an interface-trap limited regime to a bulk-limited regime. At temperatures below 250 K. the V-OC increased by up to 0.1 V as the sample was light soaked. This suggests that the interface traps limiting the V-OC can be passivated by exposure to light. (C) 2011 Elsevier B.V. All rights reserved.