Department of Electrical and Computer Engineering, McGill University, Montreal, QC, Canada.
Nanotechnology. 2010 Apr 2;21(13):134004. doi: 10.1088/0957-4484/21/13/134004. Epub 2010 Mar 8.
The presence of sodium, either in the substrate or as a co-evaporant during absorber deposition, has been shown to improve the performance of polycrystalline photovoltaic devices made with Cu(In, Ga)Se(2), as well as the ternary CuInSe(2). Investigations have shown Na or Na compounds deposited on the grain boundaries, but none have been found within intact crystal grains, leading to suggestions that grain boundaries may play a role in the improved performance of the cells. Therefore, in this study, ingots containing large monocrystals of CuInSe(2) have been grown, using a vertical-Bridgman method, from melts that also include a varying quantity of sodium. In order to simulate the conditions under which cells are constructed, a proportion of Se above stoichiometry has been added to some of the melts. Resistivity and Hall effect measurements were then performed on the material after growth. The results show no large change in either resistivity or majority hole concentration in either set of samples, although a slight decrease in the latter value was apparent in the excess Se samples with 0.2 and 0.3 at.% Na additions. No clear trend in hole mobility could be discerned, although an increase was seen with 0.2 at.% Na addition for both samples.
存在的钠，无论是在基板或作为共蒸发器在吸收器沉积，已被证明可以提高多晶光伏器件的性能，用 Cu(In, Ga)Se(2)，以及三元 CuInSe(2)。研究表明，在晶界上沉积的 Na 或 Na 化合物，但在完整的晶体晶粒内没有发现，这表明晶界可能在电池性能的提高中起作用。因此，在这项研究中，使用垂直布里奇曼法从包含一定数量钠的熔体中生长出含有大单晶 CuInSe(2)的锭。为了模拟电池制造的条件，一些熔体中添加了过量的 Se。生长后对材料进行了电阻率和 Hall 效应测量。结果表明，两组样品的电阻率或多数空穴浓度都没有明显变化，尽管在过量 Se 样品中，后者的值略有下降，Na 含量分别为 0.2 和 0.3 at.%。虽然对于两种样品，Na 含量为 0.2 at.%时空穴迁移率都有所增加，但没有明显的趋势。
