Investigations about the epitaxy of AlBGaN hetero structures for applications in UV-LEDs

AlBGaN 异质结构外延在 UV LED 中的应用研究

• 批准号: 276524601
• 负责人: Professorin Dr. Ute Kaiser
• 金额: --
• 依托单位: Zentrale Einrichtung Elektronenmikroskopie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/276524601?language=en
• 关键词: Investigations; about; epitaxy; AlBGaN; hetero

After having optimized successfully GaN-based LEDs for visible light emission, other spectral ranges move more and more into the scientific focus. In this project, we intend to concentrate on LEDs for the short wavelength ultraviolet (UV-C) spectral range, as many applications like sterilisation and disinfection of air and water become more and more interesting. Such LEDs require AlGaN hetero-structures grown on AlN (quasi) substrates. A major problem in such hetero-structures still is the fairly high defect density, partly caused by the large lattice mismatch between the different single layers and the resulting strain. Therefore, we intend to study how these problems can be managed by using boron (B) as a further component. Already quite small B fractions of a few percent can help reducing the lattice mismatch considerably. However, the incorporation of B into AlGaN is known to be limited because of a fairly small solubility. We will apply high-temperature epitaxial growth with temperatures up to 1400°C to get best solubility. Our investigations will clarify whether this indeed helps to reduce the strain in Al-containing hetero-structures - particularly in those with large Al content - without deteriorating the crystalline quality and defect density. Moreover, only scarce or even contradictory information about many fundamental properties of this quaternary material system such as band gap as function of composition, band offsets, donor and acceptor ionisation energies is currently available. By performing measurements with well-correlated methodology of various characterisation tools on our samples, we will find answers to such questions. Motivated by the very promising properties of hexagonal BN concerning p-doping with Mg, we will additionally investigate, whether this also can lead to better p-doping of AlBGaN layers.

在成功优化氮化镓基led可见光发射后，其他光谱范围越来越成为科学关注的焦点。在这个项目中，我们打算专注于短波紫外（UV-C）光谱范围的led，因为许多应用，如空气和水的灭菌和消毒变得越来越有趣。这种led需要在AlN（准）衬底上生长的AlGaN异质结构。这种异质结构的一个主要问题仍然是相当高的缺陷密度，部分原因是不同单层之间的大晶格不匹配和由此产生的应变。因此，我们打算研究如何通过使用硼(B)作为进一步的成分来管理这些问题。已经相当小的B分数（几个百分点）可以帮助大大减少晶格不匹配。然而，由于B的溶解度相当小，因此已知B与AlGaN的结合是有限的。我们将采用温度高达1400°C的高温外延生长来获得最佳的溶解度。我们的研究将澄清这是否确实有助于减少含Al异质结构中的应变，特别是在那些含Al含量高的异质结构中，而不会恶化晶体质量和缺陷密度。此外，关于这种四元材料体系的许多基本性质，如带隙作为成分的函数、带偏移、供体和受体电离能，目前只有很少甚至相互矛盾的信息。通过对我们的样本进行各种表征工具的良好相关方法的测量，我们将找到这些问题的答案。由于六方BN在p-掺杂Mg方面非常有前途的性质，我们将进一步研究这是否也可以导致更好的AlBGaN层p-掺杂。