Far Infra-Red Emission and Lasing in Doped Semiconductors

掺杂半导体中的远红外发射和激光

• 批准号: EP/E061265/2
• 负责人: Stephen Lynch
• 金额: $ 20.19万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE061265%2F2
• 关键词: Far; Infra; Red; Emission; Lasing

The terahertz band is located between the visible/near infrared frequencies and millimetre/microwave frequencies. Its physical properties bear some resemblance to light on one side and heat or microwaves on the other. It can be reflected and focused like light using special mirrors and lenses. It transfers energy/heat to materials in a similar way to microwaves, by causing the whole molecular structure to vibrate when radiation of the correct frequency is absorbed. This particular property makes terahertz radiation an ideal tool to study the properties of new materials because each material has a unique absorption signature. Why is this new and exciting? Until very recently there have been no practical sources of terahertz radiation, or indeed ways to detect it. So, in many ways this is uncharted territory. The situation changed radically with the invention (in the UK) of the first terahertz laser along with the development of a number of new techniques for producing powerful terahertz pulses.Current terahertz sources are broadly divided into two classes: broadband and single frequency. Terahertz radiation generated from photoconductive antennae and from surface fields is generally classed as broadband. The main limitation of this type of generation scheme is the low powers achieved. Lasers make up the second class, that is, single frequency terahertz sources. The III-V terahertz quantum cascade laser was first demonstrated in 2002 and considerable progress has been made since then. While the quantum cascade laser is undoubtedly an elegant device, its main disadvantage is that it requires complicated and time consuming epitaxial growth. The quantum cascade active region typically contains many hundreds of epilayers and growth times of 36 hours are not unusual.No practical materials exist with conventional bandgaps at terahertz frequencies and thus some other approach must be adopted. However, there is another fundamental energy gap in certain semiconductor materials where the energy separation lies in the terahertz frequency range. Doped semiconductors contain a series of quantized states either just below the bottom of the conduction band (donor levels) or just above the top of the valence band (acceptor levels). Under the right optical pumping conditions it has recently been shown that a population inversion can be achieved between states and stimulated emission at terahertz frequencies has been observed.The overall aim of this project is to re-visit the subject of shallow level impurities in the broad spectrum of semiconductor materials now available to us, and in doing so, open up a whole new field of terahertz laser research. Since most current commercial off-the-shelf terahertz lasers are cumbersome gas based systems, an optically pumped impurity doped semiconductor system would have an obvious size and weight advantage. Furthermore, an electrically pumped impurity based laser would have an additional advantage in that a CO2 pump laser would no longer be required. The technology, if successfully exploited, has the potential to result in a whole new breed of cheap reliable off-the-shelf sources of FIR radiation.

Terahertz带位于可见/近红外频率和毫米/微波频率之间。它的物理特性具有一定的相似之处，一侧点燃，另一侧的热或微波。可以使用特殊的镜子和镜头像光一样反映和聚焦。它以与微波相似的方式将能量/热量转移到材料中，从而导致整个分子结构在吸收正确频率的辐射时振动。这种特殊的特性使Terahertz辐射成为研究新材料特性的理想工具，因为每种材料都有独特的吸收特征。为什么这个新的令人兴奋？直到最近，还没有实用的Terahertz辐射来源，或者确实可以检测到它。因此，在许多方面，这是未知的领域。这种情况随着第一个Terahertz Laser的发明（在英国）的彻底发生变化，以及许多用于生产强大的Terahertz脉冲的新技术的开发。急剧的Terahertz源广泛分为两个类别：宽带和单个频率。从光电触角和表面场产生的Terahertz辐射通常被归类为宽带。这种类型的生成方案的主要局限性是达到的低功率。激光构成了第二类，即单频Terahertz来源。 III-V Terahertz量子级联激光器于2002年首次证明，此后已经取得了相当大的进步。虽然量子级联激光无疑是一种优雅的设备，但其主要缺点是它需要复杂且耗时的外延生长。量子级联活性区域通常包含数百个表层，生长时间为36小时并不罕见。但是，在某些半导体材料中还有另一个基本的能量差距，其中能量分离位于Terahertz频率范围内。掺杂的半导体包含一系列量化状态，要么在传导带的底部（供体水平）或价带的顶部（受体水平）上方。 Under the right optical pumping conditions it has recently been shown that a population inversion can be achieved between states and stimulated emission at terahertz frequencies has been observed.The overall aim of this project is to re-visit the subject of shallow level impurities in the broad spectrum of semiconductor materials now available to us, and in doing so, open up a whole new field of terahertz laser research.由于当前大多数商业现成的Terahertz激光器都是基于气体的系统，因此光学泵送的杂质掺杂半导体系统将具有明显的尺寸和重量优势。此外，基于电杂质的激光将具有附加优势，因为不再需要二氧化碳泵激光器。该技术如果成功地利用，则有可能导致廉价可靠的FIR辐射源廉价的新品种。

项目成果

Laboratory Scale Water Circuit Including a Photocatalytic Reactor and a Portable In-Stream Sensor To Monitor Pollutant Degradation

实验室规模水回路，包括光催化反应器和便携式流内传感器，用于监测污染物降解

• DOI: 10.1021/ie202366m
• 发表时间: 2012
• 期刊: Industrial & Engineering Chemistry Research
• 影响因子: 4.2
• 作者: Nickels P

Parameters controlling the photocatalytic performance of ZnO/Hombikat TiO2 composites

控制 ZnO/Hombikat TiO2 复合材料光催化性能的参数

• DOI: 10.1016/j.jphotochem.2011.11.001
• 发表时间: 2012
• 期刊: Chemistry
• 作者: Hamdy M

Silicon with an increased content of monoatomic sulfur centers: Sample fabrication and optical spectroscopy

单原子硫中心含量增加的硅：样品制造和光谱

• DOI: 10.1134/s1063782613020048
• 发表时间: 2013
• 期刊: Semiconductors
• 影响因子: 0.7
• 作者: Astrov Y

Time-Resolved Dynamics of Shallow Acceptor Transitions in Silicon

硅中浅受主跃迁的时间分辨动力学

• DOI: 10.1103/physrevx.3.011019
• 发表时间: 2013
• 期刊: Physical Review X
• 影响因子: 12.5
• 作者: Vinh N

Terahertz and Mid Infrared Radiation: Detection of Explosives and CBRN (Using Terahertz)

太赫兹和中红外辐射：爆炸物和 CBRN 的检测（使用太赫兹）

• DOI: 10.1007/978-94-017-8572-3_9
• 发表时间: 2014
• 作者: Lynch S