Fabrication of first 337 nm laser diodes for biological applications

最近，随着生物恐怖主义的不幸出现及其对军事目标和平民人口的威胁，有必要开发一种便携和廉价的系统，以持续监测任何开放地区、甚至在恶劣环境中从致命生物武器释放的任何潜在的气雾剂(生物颗粒)。由于大多数生物分子在280~340 nm的紫外区表现出很强的吸收，高效的紫外光光源有望成为下一代生物检测、生物成像和疾病分析应用的关键部件。特别是，使用紫外光激光二极管将使高灵敏度检测系统成为可能。III-氮化物半导体是制造这种激光二极管的最佳材料。在过去的十年里，这一领域取得了重大成就。然而，这方面的成果仅限于紫外光/蓝光区，这些器件主要基于InGaN合金。由于材料生长中的许多挑战，343 nm激光二极管是迄今报道的最短的激光二极管。显然，这样的激光二极管还不够短，不能用于上述应用。这个探索性项目的目标是开发第一个基于GaN/AlGaN材料系统的337 nm紫外激光二极管，以取代目前使用的氮气气体激光器。这项工作是基于HERE参与的英国团队在III-氮化物半导体领域的最新重大进展。这项技术的进一步应用涉及生物成像，作为一种检测人体疾病的有效方法，例如癌症组织。

Recently, with the unfortunate emergence of bio-terrorism and its threat to both military targets and civilian populations, it is necessary to develop a portable and cheap system to continuously monitor for any potential aerosolized agents (biological particles) released from deadly biological weapons in any open area, even in harsh environments. As most bio-molecules show strong absorption in the ultra-violet (UV) spectral region ranging from 280 to 340 nm, an efficient UV lighting source is expected to be a crucial component for next-generation biological detection, biological imaging and disease analysis applications. In particular use of UV laser diodes would enable high sensitivity detection systems. III-nitride semiconductors are the best materials to make such laser diodes. In last decade, there have been major achievements in this area. However, the achievements are limited to the violet/blue spectral region, with those devices mainly based on the InGaN alloy. Due to a number of challenges in material growth, a 343 nm laser diode is the shortest one so far reported. Obviously, such a laser diode is not short enough to be employable for above applications.Target of this exploratory project is the development of the first 337 nm UV laser diode based on the GaN/AlGaN material system to replace currently used N2 gas-based lasers. This work is based on recent major advances of the here involved UK teams in the field of III-nitride semiconductors. Further applications of the technology involve biological imaging as an efficient method to detect diseases in a human body, for example, cancerous tissues.