CAREER: Understanding Photo-thermoelectric Phenomena in Bulk and Nanomaterials for Better Optical Sensing

非技术红外探测器在工业、农业、医疗保健和国家安全方面有重要用途。大多数探测器都是基于半导体对红外光的吸收，而半导体又会产生电流。然而，随着波长的增加，它们的灵敏度降低，噪声增加。一种涉及光和热的不同现象表明，红外探测器在很宽的波长范围内具有高灵敏度。这种现象称为光电效应，是材料暴露于光和温度梯度时的电子响应。该职业奖将促进对光电效应的基本理解，包括材料特性的根本原因和影响。PI的团队将合成单晶薄膜和纳米材料，并通过一套先进的表征技术对其进行研究。该项目的目的是开发能够使红外探测器具有前所未有的感光性能和光谱响应的材料。该项目有一个多管齐下的教育努力，以满足国家的半导体劳动力的需求。PI将开发培训模块和快速认证计划，并探索以解决问题为重点的课程改革。本科生将参与研究，PI将参与以半导体技术为主题的K-12学生的推广活动。虽然有些可以用经典框架来描述，但其他一些则远离平衡，并且没有得到很好的理解。为了解决这一知识差距，PI将制定战略和技术，以区分不同机制的贡献，从而对每种机制进行量化和解释。光子产生的载流子的漂移将使用改进的扫描光电流显微镜检查。来自热载流子的贡献将使用瞬态光热电电压测量来区分。将使用硫化铅作为原型，比较单晶薄膜与感兴趣的纳米颗粒组件的声子瓶颈引起的缓慢的热载流子冷却的材料性能的影响进行研究。缺陷的性质及其影响将使用修改后的热电光谱技术进行研究。这些研究工作将得到泵浦探测光谱学、同步加速器衍射和吸收的补充。这项研究将使合理设计的红外传感设备的基础上的光电效应，其中不同的因素建设性地作出贡献。这个奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的知识价值和更广泛的影响审查标准。

NontechnicalInfrared detectors have important uses in industry, agriculture, healthcare, and national security. Most detectors are based on absorption of infrared light by a semiconductor that in turn generates an electrical current. However, their sensitivity decreases, and the noise increases, as the wavelength increases. A different phenomenon involving both light and heat shows promise for infrared detectors with high sensitivity across a wide range of wavelengths. This phenomenon, called the photo-thermoelectric effect, is the electronic response of a material when exposed to both light and a temperature gradient. This CAREER award will advance the fundamental understanding of the photo-thermoelectric effect, including underlying causes and impact of materials properties. The PI’s team will synthesize single crystal films and nanomaterials and study them by a suite of advanced characterization techniques. The aim of this project is to develop materials that would enable infrared of detectors with unprecedented light-sensing performance and spectral response. The project has a multi-pronged educational effort to address the nation’s semiconductor workforce needs. The PI will develop training modules and rapid certificate programs and explore curriculum reform focused on problem-solving. Undergraduate students will participate in research and the PI will engage in outreach to K-12 students themed in semiconductor technology.TechnicalPhoto-thermoelectric phenomena arise from varied mechanisms. While some can be described with classic frameworks, others occur far from equilibrium and are not well understood. In order to address this knowledge gap, the PI will develop strategies and techniques to separate contributions from different mechanisms, allowing for the quantification and interpretation of each. The drift of photon-generated carriers will be examined using modified scanning photocurrent microscopy. Contributions from hot carriers will be distinguished using transient photo-thermoelectric voltage measurements. The influence of materials properties will be studied using lead sulfide as an archetype, comparing single crystalline thin films with nanoparticles assemblies of interest for slow hot carrier cooling caused by phonon bottlenecks. The nature of defects and their influence will be studied using a modified thermoelectric spectroscopy technique. These research efforts will be complemented by pump-probe spectroscopy, and synchrotron diffraction and absorption. This research will enable rational design of infrared sensing devices based on photo-thermoelectric effects where different factors constructively contribute.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.