Research on Crystalline Compound Semiconductors and Transparent-Conducting Oxides

晶体化合物半导体和透明导电氧化物的研究

• 批准号: RGPIN-2014-04152
• 负责人: Shih, Ishiang
• 金额: $ 1.82万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=610860
• 关键词: Research; Crystalline; Compound; Semiconductors; Transparent

Part A: Monocrystalline CuInSe2 -based Semiconductors for Solar Cells The first generation commercial solar cells in the market are predominantly manufactured using bulk polycrystalline Si or monocrystalline Si. Although the thermal stability of the current Si bulk solar cells is excellent, the energy pay back time is still long. The relatively long energy pay back time is mainly due to the indirect bandgap requiring a large substrate thickness of 200 µm or more for sufficient absorption and the high growth temperatures. The energy pay back time of the second generation thin film solar cells must be reduced for large scale terrestrial applications. The way to achieve the low energy pay back time is to adopt a semiconductor with a direct band gap and high optical absorption coefficients. There are two main material systems being developed for the second generation solar cell fabrication: CuInxGa1-xSe2 and CdTe. Using these semiconductors, the amount of material usage and energy consumption during the cell manufacturing can be reduced. In the applicant’s laboratory at McGill, research work has been performed on the Bridgman growth of monocystalline CuInSe2 (CIS) and CuInGaSe2 (CIGS). Both CIS and CIGS have very large optical absorption coefficients in the solar spectrum and a thin film with a thickness as small as 0.4 µm instead of 200 µm is capable of absorbing 98% of above bandgap photons in the solar spectrum. The performance of thin film cells containing trace of Na (due to inter diffusion from soda lime glass substrates) is much better than those without Na. Unfortunately, it is more difficult to study Na effects in CIS and CIGS thin films and the causes of performance improvement have not been conclusive. Therefore, research work will be performed in this project to study effects of Na on the microscopic and electronic properties of monocrystalline bulk CIS and CIGS. Research work will be performed to prepare ingots from melts containing different amounts of Na. In addition, research work will be made to prepare photovoltaic cells on the CIS and CIGS substrates containing Na. Special attention will be paid to the effect of Na on defect density for the CIGS surface and CIS-CIGS /CdS interface face. We plan to obtain Na results which can allow thin film solar cells to reach efficiencies more than 22%. Part B: Transparent and Conducting Oxides for Electronic Applications Transparent conductive oxides (TCO) are often microcrystalline thin films which have high transmission in the visible wavelength range and high conductivity. Known TCOs include F- or Sb-doped tin oxide, Sn- or Zn-doped indium oxide and Al-, B- or Ga-doped zinc oxide. The resistivity of the TCO films is limited to a value slightly above 10-4 ohm-cm due to a relatively low mobility (~10 cm2/V-sec) at high doping density of more than 1021 cm-3. The high doping concentration has caused a decrease in optical transmission at least in the long wavelength region. In order to improve the performance of devices involving the TCOs, it is desirable to develop thin films with high electron mobility so that the doping concentration can be reduced to obtain the same level of resistivity or to decrease further the resistivity. In the present project, modulation doping will be explored in the conductive oxides in order to increase the mobility to substantially greater than 100 cm2/V-sec while maintaining the high doping concentration. The improved TCOs will be deposited on the CIS and CIGS substrates developed in part A to form solar cells. We also plan to achieve thin film transistor devices with exceptional switching performance compared to the existing technology.

A部分：基于太阳能电池的基于单晶Cuinse2的半导体 市场上的第一代商业太阳能电池主要使用散装多晶Si或单晶Si制造。尽管当前SI散装太阳能电池的热稳定性非常好，但能源还款时间仍然很长。相对长的能源还款时间主要是由于间接带隙需要200 µm或更大的底物厚度，以吸收足够的吸收和高生长温度。对于大规模的地面应用，必须减少第二代薄膜太阳能电池的能量偿还时间。实现低能付款时间的方法是采用具有直接带隙和高光学滥用系数的半导体。为第二代太阳能电池制造开发了两个主要的材料系统：Cuinxga1-XSE2和CDTE。使用这些半导体，可以减少细胞制造过程中的材料使用和能耗量。在McGill的申请人实验室中，已经对单核稳定Cuinse2（CIS）和Ciuingase2（CIGS）的Bridgman生长进行了研究工作。在太阳光谱中，顺式和CIG的光吸收系数都非常大，厚度小至0.4 µm而不是200 µm，能够吸收太阳光谱中的上述带隙照片的98％。含有Na痕迹的薄膜细胞的性能（由于苏打石灰玻璃底物的扩散引起的）比没有NA的细胞要好得多。不幸的是，在顺式和CIGS薄膜中研究Na效应更加困难，并且绩效提高的原因并不是结论性的。因此，将在该项目中进行研究工作，以研究NA对单晶体散装顺式和CIG的显微镜和电子特性的影响。将进行研究工作，以制备含有不同量NA的熔体的归纳。此外，将进行研究工作，以制备含有Na的顺式和CIGS底物上的光伏细胞。将特别注意NA对CIGS表面和顺式烟 /CD界面面的缺陷密度的影响。我们计划获得NA结果，该结果可以使薄膜太阳能电池达到效率超过22％。 B部分：用于电子应用的透明和氧化 透明的导电氧化物（TCO）通常是微晶薄膜，它们在可见的波长范围内具有较高的透射率和高电导率。已知的TCO包括F-或SB掺杂的氧化锡，Sn或Zn掺杂的氧化粘剂以及Al-，B-或GA掺杂的氧化锌。由于相对低的迁移率（〜10 cm2/v-sec）在高掺杂密度大于1021 cm-3的情况下，TCO膜的电阻限制为略高于10-4 ohm-cm的值。高掺杂浓度至少在长波长区域中导致光传递降低。为了提高涉及TCO的设备的性能，希望开发具有高电子迁移率的薄膜，以便可以降低掺杂浓度以获得相同水平的抗性或进一步降低抗性。在本项目中，将在导电氧化物中探索调节掺杂，以便在保持高掺杂浓度的同时，将迁移率提高到大大超过100 cm2/v-SEC。改进的TCO将沉积在A部分形成太阳能电池的顺式和CIGS底物上。我们还计划与现有技术相比，实现具有出色切换性能的薄膜晶体管设备。