EAGER: Self Assembled Monolayer Doping for Advanced 3D Nano & Flexible Semiconductor Structures

非技术性：电导率是一种定义电流通过材料的能力的属性。半导体的导电性可以通过引入掺杂剂，即百万分之一水平的微量杂质，来进行数量级的充电。掺杂使集成电路成为各种器件的核心成为可能。通过在工程半导体导电性、图案化以及导体和绝缘体的沉积方面的巧妙创新，半导体工业稳步地使电路更小、更快、更强大。应用涵盖计算机、通信、医疗保健和能源，导致物联网（IoT）的出现。大多数当前的掺杂技术依赖于平面刚性衬底。为了达到下一个前沿，需要设计新的原子级化学方法，以在三维中的精确位置存款掺杂剂分子的多层。分子单层掺杂（MLD）是一种能够产生平面和非平面结构超浅结的掺杂方法。MLD的低成本反应室使用的材料通常在化学仓库和当地家居用品商店中找到。MLD目前处于原子层沉积在70年代早期和离子注入在60年代早期的阶段。这两种技术现在都是大批量生产技术。PI将优化掺杂剂原子到硅表面的自组装，具有纳米级的形貌，以创建未来的计算，物联网和能源设备。它将为化学和电子学之间的研究和教育提供一个很好的桥梁。技术：拟议工作的目标是演示低电压，二维材料为基础的相变开关在射频（RF）频率的操作。在具有多频带发射/接收能力的无线系统中，可重新配置的RF前端电路需要开关。与固态或机电开关相比，相变开关具有低损耗、高截止频率、高隔离度和快速开关等优点。二维（2D）碲化钼（MoTe 2）已被证明具有相变特性，理论上预计的电压要求显著低于传统薄膜相变材料。低电压开关，加上灵活性和透明度，使2D相变开关有吸引力的候选人为下一代，移动的纳米系统。拟议的工作将实验验证和表征大面积，2D MoTe 2 RF开关。这将涉及设备的制造，以及低电压和频率响应性能限制的实验探索。这些结果将是关键的相变器件的未来发展，预测模型的建立和可重构纳米电路的演示。该EAGER方案的智力价值包括以下内容：（1）探索并建立对应用于2D MoTe 2和相关允许的相位控制技术（例如热量和电压）之间的权衡的基本理解，以建立行为模型并实现低能量开关器件;（2）解锁2D相变膜的大面积化学气相沉积（CVD），特别关注低能量相变的厚度控制，以及高频操作的增加的迁移率;以及（3）建立使用2D相变材料的第一RF开关的基本设计程序，其将通过制造和表征来验证。这项工作的成果将对低功耗无线电路产生巨大影响，并加速物联网及其他领域无线传感器节点的出现。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical:Electrical conductivity is a property that defines the ability to pass electric current through a material. The conductivity of semiconductors can be charged by orders of magnitudes by introducing dopants, trace impurities at the levels of parts per million. Doping makes possible the integrated circuits at the heart of a wide range of devices. Through clever innovations in engineering semiconductor conductivity, patterning, and deposition of conductors and insulators, the semiconductor industry has steadily made circuitry smaller, faster, and more powerful. Applications span computers, communications, healthcare and energy, leading to the emergence of the Internet of Things (IoT). Most current doping techniques rely on planar rigid substrates. To reach the next frontier, there is need to devise new atomic scale chemical means to deposit ultrathin layers of dopant molecules in precise locations in three dimensions. Molecular monolayer doping (MLD) is a doping method with the capability to produce ultra-shallow junctions for planar and non-planar structures. A low-cost reaction chamber for MLD uses materials that are commonly found in chemistry stockrooms and local home goods stores. MLD is presently at a stage where atomic layer deposition was in the early 70s and ion implantation was in the early 60s. Both are now high volume manufacturing techniques. The PIs will optimize self-assembling of dopant atoms into the silicon surface with topography at nanoscales to create futuristic computing, IoT and energy devices. It will provide an excellent research and education bridge between chemistry and electronics.Technical:The objective of the proposed work is to demonstrate the operation of low voltage, 2D material-based phase change switches at radio-frequency (RF) frequencies. Switches are required for reconfigurable RF front-end circuits in wireless systems with multi-band transmit/receive capabilities. Compared to solid-state or electro-mechanical, phase change switches promise low loss, high cut-off frequencies, high isolation and rapid switching. Two-dimensional (2D) molybdenum telluride (MoTe2) has been shown to demonstrate phase change properties, with theoretically projected voltage requirements significantly lower than traditional thin film phase change materials. Low voltage switching, coupled with flexibility and transparency make 2D phase change switches attractive candidates for next-generation, mobile nanosystems. The proposed work will experimentally validate and characterize large area, 2D MoTe2 RF switches. This will involve fabrication of the devices, as well as experimental exploration of the low-voltage and frequency response performance limits. These results will be key to the future development of phase change devices, the establishment of predictive models and the demonstration of reconfigurable nano-circuits. The intellectual merit of this EAGER proposal comprises of the following: (1) exploring and establishing a fundamental understanding of trade-offs between phase control techniques, such as heat and voltage, applied to 2D MoTe2 and related allows in order to establish behavioral models and achieve low-energy switching devices; (2) unlocking large-area chemical vapor deposition (CVD) of 2D phase change films, paying particular attention to thickness control for low-energy phase transitions, as well as increased mobility for high-frequency operation; and (3) establishing basic design procedures for the first RF switches using 2D phase change materials, which will be validated through fabrication and characterization. This results of proposed work stand to have immense implications for low-power wireless circuits and accelerate the advent of wireless sensor nodes within the Internet of Things and beyond.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.