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

合作研究：利用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对于热功率转换、非接触式热管理、热成像和激光制造至关重要，其中高度期望动态可调谐的热发射或吸收具有良好的可控性和通用性。我们的目标是采用金属氧化物半导体（MOS）纳米结构，通过电调谐超过远场黑体极限的热通量，实现显着的调制辐射热传递。该项目的成功将最终导致可调热电转换，热控制，热电路与热光子手段的新应用。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。PI将培训下一代劳动力，重点是女性和少数民族学生等代表性不足的群体的更广泛参与。研究生将学习多个学科的基础知识，这将为他们解决工程界未来的能源挑战做好准备。ASU和UA的本科研究项目为本科生提供了一个很好的机会，让他们参与PI实验室的研究活动。PI将通过ASU和UA的各种外展计划吸引本地K-12学生，旨在激发他们对STEM的兴趣。众所周知，平面MOS结构的电容随着栅极电压而变化，这会导致半导体内自由电荷载流子的耗尽或积累，但它只发生在非常接近氧化物界面的半导体有源区中，大约为10 nm，近似于德拜长度。由于平面半导体的红外穿透深度为微米量级，在这种半导体有源区内的吸收变化几乎不会在整个结构内引起明显的调制吸收/发射。所提出的近场MOS纳米结构将克服这一挑战，通过利用鳍式场效应晶体管与环绕的金属氧化物电极和氧化物栅极层以及近场效应。直径约为几十纳米的半导体纳米结构的载流子浓度将随着电选通时的耗尽或积累而显著变化。纳米结构层的急剧变化的介电函数将导致电调制的近场辐射传热。通过将MOS纳米结构放置在具有纳米间隙距离的发射表面附近，可以发生具有耦合倏逝波的近场效应，以增强辐射能量，显著超过远场黑体极限。该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、样品制造和表征、近场测量和计量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。

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