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

非技术性：导电性是一种定义电流通过材料的能力的特性。通过引入杂质，半导体的导电性可以按数量级充电，在百万分之几的水平上引入痕量杂质。掺杂使各种设备的核心集成电路成为可能。通过在设计半导体导电性、图案化以及导体和绝缘体沉积方面的巧妙创新，半导体行业稳步地使电路变得更小、更快、更强大。应用横跨计算机、通信、医疗保健和能源，导致了物联网(IoT)的出现。目前的大多数掺杂技术都依赖于平面刚性衬底。为了达到下一个前沿，需要设计出新的原子尺度的化学方法，在三维空间的精确位置沉积超薄的掺杂分子。分子单层掺杂(MLD)是一种能够在平面和非平面结构中产生超浅结的掺杂方法。MLD的低成本反应室使用了化学仓库和当地家居用品商店中常见的材料。MLD目前处于原子层沉积在70年代初，离子注入在60年代初的阶段。这两种技术现在都是大批量生产技术。PI将优化掺杂原子在纳米级表面的自组装，以创造未来的计算、物联网和能源设备。它将在化学和电子学之间架起一座极好的研究和教育桥梁。技术：拟议工作的目标是演示低电压、2D材料相变开关在射频(RF)频率下的操作。在具有多频带发送/接收功能的无线系统中，可重新配置的射频前端电路需要开关。与固态或机电开关相比，相变开关具有损耗低、截止频率高、隔离度高、开关速度快等优点。二维(2D)碲化钼(MoTe2)材料具有良好的相变特性，其理论电压要求远低于传统的薄膜相变材料。低电压开关，再加上灵活性和透明性，使得2D相变开关成为下一代移动纳米系统的候选开关。所提出的工作将在实验上验证和表征大面积的2D MoTe2射频开关。这将涉及到器件的制造，以及对低电压和频率响应性能极限的实验探索。这些结果将对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起到关键作用。这项急切的建议的智力优势包括：(1)探索并建立对应用于2D MoTe2及相关设备的热和电压等相控制技术之间的权衡的基本认识，以建立行为模型和实现低能量开关器件；(2)解锁2D相变薄膜的大面积化学气相沉积(CVD)，尤其关注低能相变的厚度控制，以及提高高频操作的迁移率；以及(3)建立第一批使用2D相变材料的射频开关的基本设计程序，这些程序将通过制造和表征进行验证。这项拟议工作的结果将对低功率无线电路产生巨大影响，并加速物联网内外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。

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.