基于CdO的透明导电氧化物薄膜的研究和应用

Transparent conducting oxides (TCOs), which transmit light and conduct electrical current simultaneously, have been the important part of the solar cells, panel displays, and so on. Among all potential TCOs, cadmium oxide (CdO) has the highest reported mobility values. The conductivity of CdO could be improved higher than ITO be doping with different elements. In addition, it has high transmission for long wavelength IR light of sunlight. Moreover, the TCO thinfilms based CdO could be deposited at lower temperature and have good thermal stable.. We plan to research the doping of CdO systematically, doped with In、Ga、Ti、Y、Zn, and so on. To understand the relation between the dopants, prepared conditions and the conductivity, transmission. We want to achieve the modulation of the carrier mobility, carrier concentration, band gap, IR transmission. We plan to doped CdO with two different elements at same time, such as In/Zn、Ti/In. And obtain the TCO thinfilms with high conductivity and large transparent range at the same time.. Moreover, we want to research the application of these TCO thinfilms in solar cells, such as Si or CdTe solar cells. And compare the properties of the solar cells use ITO、FTO as the TCO layer. The application of the TCO in solar cells could give some feedback for the research of TCO based on CdO. This may improve efficiency of the solar cells because of their high conductivity and large transparent range.

透明导电氧化物（TCO）薄膜由于同时具有良好的导电性和光透过率的特性，已经成为太阳能电池、平板显示等器件的重要组成部分。在潜在的TCO材料中，CdO具有最高的已报道载流子迁移率，通过掺杂可以具有比ITO更高的导电性和红外透过率，同时它具有更低的沉积温度和更好的热稳定性。. 我们拟利用射频溅射的制备方法对CdO进行系统的掺杂研究，掺入In、Ga、Ti、Y、Zn等元素，理解掺杂和制备条件对导电性、透过率及透过范围的影响，实现对载流子迁移率、载流子浓度、带隙、红外透过范围的调制。在单一元素的掺杂基础上进行二元掺杂的研究，比如In/Zn、Ti/In，得到同时具有高导电性和宽透过范围的TCO薄膜。同时也拟将基于CdO的TCO薄膜应用于Si、CdTe等太阳能电池，并与传统的ITO、FTO等TCO材料进行比较。通过实际应用的反馈，来指导CdO基TCO薄膜的研究，提高太阳能电池的光电转化效率。

目前ITO（掺Sn的In2O3）、FTO（掺F的SnO2）、AZO（掺Al的ZnO）是最主要的三种应用于太阳能电池的TCO材料[3]。其中ITO的导电性较好，应用也最广泛，电阻率可以达到1×10-4 Ω•cm左右，而FTO和AZO相对较差些，电阻率约10-4~10-3 Ω•cm。相较于传统的TCO材料，CdO具有高迁移率、低吸收率等特点，虽然本征带隙较小（~2.2eV）但通过掺杂后可以达到大于3.2eV，因此可以同时兼具高导电性和高透过率的特点。. 我们研究了不同元素掺杂CdO后的结果，获得了电阻率小7x10-5 Ω•cm，同时吸收边大于3.3eV的透明导电薄膜，导电性比商用ITO更好。因此是一种很有潜力的透明导电材料。. 同时我们也发现通过调节镀膜工艺，控制CdO薄膜的载流子浓度在3x10 20/cm3以内，可以获得在近红外甚至中红外区域具有高透过率（95%），同时具有100欧姆面电阻的透明导电薄膜，这是目前ITO等商用薄膜说不具备的，在高功率CO2激光器以及通讯领域有潜在的应用。