Collaborative Research: Electrically Modulated Near-field Thermophotonics with Metal-Oxide-Semiconductor Nanostructures

合作研究：具有金属氧化物半导体纳米结构的电调制近场热光子学热光子学在热能转换、非接触式热管理、热成像和激光制造中至关重要，这些领域非常需要动态可调的热发射或吸收，具有很强的可控性和通用性。我们的目标是利用金属氧化物半导体(MOS)纳米结构，通过电调谐热通量超过远场黑体极限来实现对辐射热的显著调制。该项目的成功将最终导致可调谐热电转换、热控制、具有热光手段的热电路的新应用。研究成果将通过期刊出版物、会议报告和课程教学迅速传播。PIS将培训下一代劳动力，重点是女性和少数族裔学生等代表性不足的群体更广泛地参与。研究生将学习多个学科的基础知识，这将使他们为解决未来工程界的能源挑战做好准备。亚利桑那州立大学和亚利桑那州立大学的本科生研究项目为本科生提供了一个很好的机会，让他们参与PIS实验室的研究活动。PIS将通过亚利桑那州立大学和亚利桑那州立大学的各种外展项目吸引当地K-12学生，旨在激发他们对STEM的兴趣。众所周知，平面MOS结构的电容随栅电压的变化而变化，这会导致半导体中自由载流子的耗尽或积累，但它只出现在距离氧化层界面非常近的超薄有源区，其量级约为10 nm，与德拜长度近似。当平面半导体的红外穿透深度在微米量级时，这种超薄有源区的吸收变化在整个结构内几乎不会引起明显的调制吸收/发射。所提出的近场MOS纳米结构将通过使用鳍场效应晶体管来克服这一挑战，该晶体管具有包裹的超薄金属电极和氧化物栅层以及近场效应。直径在几十纳米左右的半导体纳米结构的载流子浓度会随着电栅的耗尽或积累而发生显著的变化。纳米结构层介电函数的急剧变化将导致近场辐射换热的电调制。通过将MOS纳米结构放置在具有纳米间距的发射面附近，可以发生耦合逝去波的近场效应，从而使辐射能量大大超过远场黑体极限。拟议的研究项目将结合理论和实验任务进行，包括设计和理论建模、样品制作和表征、近场测量和计量学开发，以及验证和优化。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。

Collaborative Research: Electrically Modulated Near-field Thermophotonics with Metal-Oxide-Semiconductor Nanostructures Thermophotonics is crucial to heat-to-power conversion, non-contact thermal management, thermal imaging, and laser manufacturing, where dynamically tunable thermal emission or absorption are highly desired with great controllability and versatility. We aim to employ metal-oxide-semiconductor (MOS) nanostructures to achieve significant modulation of radiative heat transfer via electrical tuning with heat flux exceeding the far-field blackbody limit. The success of this project would ultimately lead to novel applications of tunable thermoelectric conversion, heat control, thermal circuits with thermophotonic means. The research outcomes will be quickly disseminated through journal publications, conference presentations and course teaching. The PIs will train the next generation of workforce with an emphasis on broader participation of underrepresented groups such as female and minority students. Graduate students will learn the fundamentals of multiple disciplines, which will well prepare them for solving future energy challenges in engineering communities. The undergraduate research programs at ASU and UA offer a great opportunity for undergraduate students to participate in the research activities in the PIs’ labs. The PIs will engage local K-12 students through various outreaching programs at ASU and UA, aiming to spark their interests in STEM. It is known that the capacitance of planar MOS structures varies with the gate voltage which causes depletion or accumulation of free charge carriers within the semiconductor, but it occurs only in the ultrathin active region very close to the oxide interface on the order of ~10 nm approximated by the Debye length. With the infrared penetration depth of planar semiconductor on the order of micrometers, the absorption variation within such ultrathin active region could barely cause appreciable modulation absorption/emission within the whole structure. The proposed near-field MOS nanostructure would overcome this challenge by utilizing a fin field-effect transistor with the wrap-around ultrathin metal electrode and oxide gate layers as well as near-field effect. The carrier concentration of the semiconductor nanostructures whose diameter is about several tens of nanometers will change significantly with depletion or accumulation upon electrical gating. The drastically varied dielectric functions of the nanostructure layer will lead to electrically modulated near-field radiative heat transfer. By placing the MOS nanostructure in close proximity to an emitting surface with nanometric gap distances, the near-field effect with coupled evanescent waves could occur to enhance the radiative energy significantly surpassing the far-field blackbody limit. The proposed research project will be carried out with a combination of theoretical and experimental tasks including design and theoretical modeling, sample fabrication and characterization, near-field measurements and metrology development, as well as validation and optimization.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.