摘要：在过去的二十年中我们已经对金属氧化物薄膜进行了广泛的研究。人们之所以对这些材料具有广泛兴趣，是因为他们可以在很宽的波长范围内同时具备高导电性和透明性。如氧化铟锡氧化物（ITO）或氧化锌铝（AZO）被广泛应用于薄膜太阳能电池透明的接触。在这些氧化物的应用的一个重要的限制是，它们有明显的长波长的吸收，因此不能用于利用太阳光谱的红外部分的太阳能电池。这些材料的可怜的红外透过率可以归因于较强的电离杂质散射导致的低流动性和大量的自由载流子的吸收。此外，由于这些材料的高电子浓度（~1021／cm3）等离子体反射通常发生在< 1200nm波长。62780

    合成CdO（故意掺杂掺杂如In或GA）具有很高的电子迁移率并且红外透过率特别高。这可以归因于CdO的独特的电子结构和极低的导带边缘以及小电子的有效质量。这些掺杂的CdO的一个缺点是相对较小的带隙限制紫外线（UV）透光边缘只有~400 nm，限制了太阳光谱的紫外线部分的有效利用。掺杂的CdO的紫外吸收边的~2.2 eV和Burstein-Moss漂移在材料中的电子浓度大直接导致导带中的费米能级的带隙位置高相关的确定。由于实现了掺杂超过1021 立方厘米CdO的电子浓度已经非常高，转移到更高的能量吸收边的唯一可行的办法是增加内在能量的差距。在本文中我们探讨合金CdO与MgO在7.8 eV的能隙向上移位的吸收边和提高最终的CdMgO合金的紫外线透过率。

毕业论文关键词：太阳光谱，散射，自由载流子，带隙

Abstract：Metal oxides have been extensively studied over the last two decades. The reason for the wide interest in these materials is that they can be highly conductive and transparent over a wide wavelength region at the same time. Wide gap oxides such as In2O3:Sn (ITO) or ZnO:Al (AZO) are widely used as transparent contacts on thin film solar cells. An important limitation in the applications of these oxides is that they have significant long wavelength absorption and thus cannot be used for photovoltaics that utilize the infrared part of the solar spectrum. The poor infrared transmittance of these materials can be attributed to the relatively strong ionized impurity scattering resulting in low mobility and large free carrier absorption. In addition, due to the high electron concentration in these materials (∽1021/cm3) their plasma reflection edge typically occurs at wavelengths <1200nm.

    It has been shown recently that it is possible to synthesize an intentionally doped CdO (with dopants such as In or Ga)with very high electron mobilities and exceptionally high infrared transmittance. This can be attributed to the unique electronic structures of the CdO with extremely low conduction band edge and small electron effective mass.A drawback of these doped CdO is their relatively small bandgap that limits the ultraviolet (UV) transmittance edge to only ∽400 nm that is not sufficient for an efficient utilization of the UV part of the solar spectrum. The UV absorption edge of the doped CdO is determined by the intrinsic direct gap of∽2.2 eV and the Burstein-Moss shift associated with the high location of the Fermi energy in the conduction band resulting from the large concentration of electrons in the material.Since the achieved electron concentrations of more than 1021 cm-3 in doped CdO are already extremely high, the only viable way of shifting the absorption edge to higher energy is to increase the intrinsic energy gap. In this paper we explore alloying CdO with MgO with the energy gap of 7.8 eV to upward shift the absorption edge and improve the UV transmittance of the resulting CdMgO alloys.

Key Words：the solar spectrum, scattering, free carrier, band gap 

1  绪论··5

 1.1  透明导电薄膜发展简史·5