Beyond Blue: New Horizons in Nitrides (Platform Grant Renewal)

我们的研究是基于氮化镓及其合金，这是一种神奇的材料家族，可以发出从红外（IR）到紫外线（UV）的各种颜色的光。这些材料已经广泛应用于作为我们日常生活一部分的发光器件中，也许最常见的是蓝光发光二极管（led）和激光二极管（ld）。led是蓝光HD-DVD播放器的核心，而蓝色led与发出其他颜色光的荧光粉结合在一起，产生白光。这种白光led现在在自行车灯、手电筒和从移动电话到平板电脑等便携式电子设备的背光显示中非常常见。十多年来，剑桥大学和曼彻斯特大学一直在合作开发蓝色led的材料。我们的研究使人们对发光材料的基础材料科学和物理学的理解发生了翻天覆地的变化，从而提高了led的效率。此外，我们还开创了低成本的方法，用于商业化led中使用的氮化镓晶体的生长，目前正在由一家英国公司Plessey开发，他们正在普利茅斯的英国工厂制造这些设备。虽然我们的目标是继续与我们的工业合作伙伴合作，提高我们的蓝色LED技术的性能和成本，实现新的应用，例如在医疗保健系统中，我们现在正在寻找超越蓝色LED的氮化镓的其他应用，例如将在光谱的绿色和紫外线部分发射光的设备。目前，在绿色和紫外线中发射的氮化物器件的效率远低于蓝色led，这一限制阻碍了氮化物在整个光谱中的充分利用。运用剑桥-曼彻斯特大学成功的方法来理解材料属性背后的基础科学，并以此来推动设备开发，我们的目标是生产用于显示器和高质量家庭和办公室白色照明的绿色led。也许更重要的是，UV led可以是一种低能耗的方式来净化饮用水，这可以挽救发展中国家数百万人的生命，我们正在考虑创新的方法来开发这些设备。展望led之外，我们将开展led甚至单光子源的研究。后一种器件可以按需发射一个且仅一个光子，是量子密码和量子计算的使能技术。我们在设计和制造蓝色单光子源方面已经处于世界领先地位。我们希望探索的视野不一定是新的颜色，而是具有惊人新功能的设备，比如发射纠缠光子对。纠缠——阿尔伯特·爱因斯坦称之为“幽灵般的超距作用”——是一种奇特的现象，即使一对纠缠的粒子相隔数英里，其中一方的变化也会影响另一方。缠结可以用来实现完全安全的信息传输。氮化镓也可以用于电子设备，因此剑桥和曼彻斯特的另一个新兴研究主题是氮化晶体管的开发，这将减少在高功率应用（如计算机电源、电机驱动器或光伏系统的电源逆变器）中作为热量浪费的能量。总的来说，我们的研究有潜力为数百万人提供清洁的水，大大减少能源消耗和温室气体排放，并实现完全安全的通信，但GaN还有许多新的应用前景，我们希望这个平台的资助将帮助我们保持英国在这一杰出发展技术的前沿。

Our research is based on gallium nitride and its alloys, an amazing family of materials which can emit light over a wide range of colours - from the infra-red (IR) to the ultra-violet (UV). Already these materials are widely used in light emitting devices that are part of our everyday lives, perhaps most commonly in blue light emitting diodes (LEDs) and laser diodes (LDs). The LDs are at the heart of the blu-ray HD-DVD player, whilst the blue LEDs are combined with phosphors that emit other colours of light to produce white light. Such white LEDs are now very common in bicycle lights, torches and back-lighting for displays on portable electronic devices from mobile phones to tablet computers.Cambridge and Manchester have been collaborating on materials for blue LEDs for over ten years. Our research has led to step changes in the understanding of the basic materials science and physics of the light emitting materials leading to improved LED efficiency. Also we have pioneered lower cost methods for the growth of the gallium nitride crystals used in LEDs which have been commercialised, and are currently being exploited by a UK company, Plessey, who are fabricating these devices at their UK factory in Plymouth. Whilst we aim to continue to improve both the performance and cost of our blue LED technology in collaboration with our industrial partners, enabling new applications, e.g. in health care systems, we are now looking beyond the blue LED to other applications of gallium nitride such as devices that will emit light in the green and UV parts of the spectrum. Currently nitride devices emitting in the green and UV have much lower efficiencies than blue LEDs, and this limitation prevents the full exploitation of the nitrides across the whole spectrum. Applying the successful Cambridge-Manchester approach of understanding the basic science underlying the materials' properties, and using this to drive device development, we aim to produce green LEDs for application in displays and in high quality white lighting for homes and offices. Perhaps even more significantly, UV LEDs could be a low-energy way to purify drinking water, which could save millions of lives in the developing worlds, and we are considering innovative approaches to the development of these devices. Looking beyond LEDs, we will carry out research on LDs and even single photon sources. These latter devices, which emit one -and only one - photon on demand, are an enabling technology for quantum cryptography and quantum computation. We are already world leaders in the design and fabrication of blue single photon sources. The horizons we wish to explore are not necessarily new colours but devices with astounding new capabilities, such as the emission of pairs of entangled photons. Entanglement - which Albert Einstein referred to as "spooky action at a distance" - is a peculiar phenomenon by which changes made to one of the entangled pair of particles affect the other, even if the two are many miles apart. Entanglement can be used to achieve totally secure transfer of information. Gallium nitride can also be used in electronic devices, and so another emerging research theme at Cambridge and Manchester is the development of nitride transistors which will reduce the energy wasted as heat in high power applications such as computer power supplies, motor drives or power inverters of photovoltaic systems.Overall, our research has the potential to provide clean water for millions, vastly reduce energy consumption and greenhouse gas emissions and to enable totally secure communications but there are many new applications on the horizon for GaN, and we hope that this platform grant will help us to keep the UK at the forefront of this outstanding developing technology.