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

我们的研究基于氮化镓及其合金，这是一种令人惊叹的材料家族，可以发出各种颜色的光-从红外线（IR）到紫外线（UV）。这些材料已经广泛用于我们日常生活中的发光器件，也许最常见的是蓝光发光二极管（LED）和激光二极管（LD）。LD是蓝光HD-DVD播放器的核心，而蓝光LED与发出其他颜色光的磷光体结合，产生白色光。这种白色LED现在在自行车灯、手电筒和从移动的手机到平板电脑的便携式电子设备上的显示器的背光中非常常见。剑桥和曼彻斯特已经在蓝色LED的材料上合作了十多年。我们的研究导致了对发光材料的基础材料科学和物理学的理解的逐步变化，从而提高了LED的效率。此外，我们还开创了低成本的方法来生长用于LED的氮化镓晶体，这些方法已经商业化，目前正在由一家英国公司Plessey开发，该公司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提高我们的蓝色LED技术的性能和成本与我们的工业合作伙伴合作，使新的应用，如在医疗保健系统，我们现在正在寻找超越蓝色LED氮化镓的其他应用，如设备，将发射光在绿色和紫外线部分的光谱。目前，在绿色和UV中发射的氮化物器件具有比蓝色LED低得多的效率，并且这种限制阻止了氮化物在整个光谱上的充分利用。应用成功的剑桥-曼彻斯特方法，了解材料特性的基础科学，并以此推动设备开发，我们的目标是生产绿色LED，用于显示器和家庭和办公室的高质量白色照明。也许更重要的是，紫外线LED可以成为一种低能耗的饮用水净化方式，这可以挽救发展中国家数百万人的生命，我们正在考虑开发这些设备的创新方法。展望LED之外，我们将开展LD甚至单光子源的研究。后一种设备按需发射一个（且仅一个）光子，是量子密码学和量子计算的一种使能技术。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，例如发射纠缠光子对。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，通过这种现象，纠缠粒子对中的一个粒子的变化会影响另一个粒子，即使这两个粒子相距很远。纠缠可以用来实现完全安全的信息传输。氮化镓还可以用于电子设备，因此剑桥和曼彻斯特的另一个新兴研究主题是氮化物晶体管的开发，这将减少在高功率应用中浪费的能量，如计算机电源，电机驱动器或光伏系统的功率逆变器。总的来说，我们的研究有可能为数百万人提供清洁水，虽然GaN技术的应用可以大大降低能源消耗和温室气体排放，并实现完全安全的通信，但GaN技术还有许多新的应用前景，我们希望这项平台资助将有助于我们使英国保持在这项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.