EAGER: Low-Temperature Plasmas for Synthesis of Diamond Nanoparticles

虽然钻石被视为宝石，但很少有人意识到钻石为光电设备提供的巨大技术潜力。钻石是一种宽禁带半导体，具有极高的导热系数，使其成为一系列应用的首选材料，包括量子计算、植入式生物医学设备和高压电子设备--这些应用超出了工业钻石的传统切割钻头用途。当钻石以纳米颗粒的形式制造时，由于尺寸引起的性能变化以及将纳米颗粒引入薄膜应用的简便性，其能力会增加。挑战在于，以可扩展的方式合成高质量的金刚石纳米颗粒是困难的，而且关于钻石纳米颗粒是如何产生的，存在许多科学知识空白。碳-碳键可以形成石墨或钻石，控制在反应过程中产生哪一个键仍然是一个悬而未决的问题。这项研究计划打算扩展令人兴奋的早期结果，这些结果表明可以在低温等离子体(LTP)反应器中形成钻石纳米颗粒，这一方法有望对如何高质量和高产量地生产钻石有新的理解。这项研究的预期结果是发现了控制流通式LTPS中金刚石生长的新反应路径，具有在反应过程中选择键形成的能力。如果成功，这项工作将能够为各种关键应用创造钻石纳米颗粒，并为其他半导体纳米材料的LTPS中的键形成产生新的知识。拟议的研究还将与外联活动结合使用，以鼓励未被充分代表的群体参与工程。纳米颗粒的低温等离子体(LTP)合成因这些反应堆以可扩展的方式生产高质量和可调性能纳米颗粒的能力而受到越来越多的关注。LTP合成纳米颗粒的根本挑战是关于反应器参数如何直接影响纳米颗粒生长的知识空白。这一挑战在碳系统的背景下被放大了，该系统的特点是sp2和sp3杂化，导致了截然不同的碳基材料，即石墨烯/石墨和钻石。在这项工作中，在有希望的初步结果的基础上，通过控制等离子体和反应器参数，在射频和微波LTP反应器中进行选择性键杂交以合成金刚石纳米颗粒。由于纳米颗粒的尺寸特性，专注于纳米颗粒的合成可以增加功能的可调性。LTP反应器的独特之处在于，它们可以控制各种纳米晶体的性能，包括尺寸、表面功能和掺杂，以及使用惯性撞击、扩散甚至直接写入图案的受控沉积。这项研究将在反应堆操作参数和所产生的纳米颗粒特性之间产生一幅图，包括发现在反应过程中选择键杂交所需的条件。拟议的工作将建立纳米晶体成核和生长如何发生的基本图景，填补在理解与石墨合成相比，在LTP反应堆中合成钻石的确切能量和生长条件要求方面的关键空白。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

While diamonds are prized as gemstones, few realize the immense technological potential that diamond offers for optoelectronic devices. Diamond is a wide-bandgap semiconductor with extraordinarily high thermal conductivity, making it a material of choice for a range of applications including quantum computing, implantable biomedical devices, and high-voltage electronics – applications beyond the traditional cutting bit uses of industrial diamonds. When diamond is made in nanoparticle form, its capabilities increase because of size-induced changes to properties and the ease of incorporating nanoparticles into thin film applications. The challenge is that synthesizing diamond nanoparticles with high quality and in a scalable manner is difficult, and there are many scientific knowledge gaps on how diamond nanoparticles are created. Carbon-carbon bonds can form either graphite or diamond, and control over which bond is generated in reactive processes remains an open problem. This research plan intends to expand on exciting early results indicating that diamond nanoparticles can be formed in low-temperature plasma (LTP) reactors, in an approach that promises new understanding of how diamond can be generated with high quality and high yield. The expected results of this research are the discovery of new reaction pathways to control diamond growth in flow-through LTPs with the capability to select bond formation during the reaction. If successful, this work will enable the creation of diamond nanoparticles for a variety of critical applications, as well as generate new knowledge around bond formation in LTPs for other semiconductor nanomaterials. The proposed research will also be used in conjunction with outreach events to encourage participation of underrepresented groups in engineering.Low-temperature plasma (LTP) synthesis of nanoparticles has gained growing attention for the ability of these reactors to produce high-quality and tunable-property nanoparticles in a scalable manner. The fundamental challenge in LTP synthesis of nanoparticles is a gap in knowledge about how reactor parameters directly influence nanoparticle growth. This challenge is amplified in the context of the carbon system, which features both sp2 and sp3 hybridization that result in dramatically different carbon-based materials – namely, graphene/graphite and diamond. In this work, based on promising preliminary results, selective bond hybridization in radiofrequency and microwave LTP reactors via control over plasma and reactor parameters will be investigated for synthesis of diamond nanoparticles. Focusing on synthesis of nanoparticles allows for added functional tunability because of size-dependent properties. LTP reactors are unique in that they offer control over a variety of nanocrystal properties, including size, surface functionality, and doping together with controlled deposition using inertial impaction, diffusion, or even direct-write deposition into patterns. This research will produce a map between reactor operating parameters and resulting nanoparticle properties, including discovering the conditions that are required for selected bond hybridization during the reaction. The proposed work will build a fundamental picture of how nanocrystal nucleation and growth occur, filling a critical gap in understanding about the exact energetic and growth condition requirements for diamond synthesis, as compared to graphite synthesis, in LTP reactors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.