Scanned Probe Microscopy using Single-Electron Device Arrays

使用单电子器件阵列的扫描探针显微镜

• 批准号: 1509087
• 负责人: Gregory Snider
• 金额: $ 38万
• 依托单位: University of Notre Dame
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1509087&HistoricalAwards=false
• 关键词: Scanned; Probe; Microscopy; using; Single

This project will use ultra-sensitive charge detectors coupled to a scanning needle, similar to an Atomic Force Microscope, to make nanoscale-resolution maps of the electrical potential of a surface of solid or soft materials. A novel sensor, based on high-speed version of the most sensitive charge detector, single-electron transistor (SET), will be used. This sensor employs arrays of SETs and radio-frequency reflectometry to give information on fast charging processes, occurring in a microsecond time frame. The capabilities of this technique enable experiments that cannot be performed using traditional measurements of surface potentials. For instance, in existing measurements the scanning probe disturbs the surface that is being measured, making it difficult to measure charges, such as electrons, that are only weakly confined to an area of the surface. In contrast, the measurements made in this project will be much less disruptive to the surface, making it possible to observe phenomena such as Wigner localization of electrons. The project also involves an outreach program that will target middle school students in South Bend Schools through classroom activities involving faculty and graduate students, and field trips to bring students to the Notre Dame labs. These activities will contact 50 - 100 students per year. Middle school aged children are an excellent group for outreach since they are advanced enough to understand science, but are still making choices about their areas of interests. South Bend public schools have a diverse student population with a large number of students from groups underrepresented in the areas of science and technology.This project will use ultra-sensitive electrometers coupled to a scanned probe system to map the potential of material surfaces. In surface potential measurements, two methods dominate: Kelvin Probe Force Microscopy (KPFM) and Electrostatic Force Microscopy (EFM). Kelvin probe is the more popular technique because it produces a quantitative measurement of the contact potential difference (CPD) while EFM can measure only qualitative changes in CPD. This project design and fabricate scanning single-electron transistor probes (S-SETs) and use them to characterize the surface charge and potential of semiconductor surfaces. The S-SET probes will use radio-frequency reflectometry to enable measurements of the CPD with high charge and potential sensitivity, as well as high spatial and temporal resolution. Arrays of SETs will be used to provide improved immunity to random background charge fluctuations, and to provide improved matching to the RF circuit, eliminating the need for a complicated resonant network. In addition, the use of an RF SET will enable a Kelvin force measurement, not yet reported in the literature, that will be less invasive than those made by conventional KPFM. With the scanned probe system it will be possible to characterize a variety of surfaces including semiconductors and insulators. In particular, the system will be used to investigate Wigner localization of electrons within semiconductor quantum dots.

该项目将使用与扫描针（类似于原子力显微镜）结合的超敏感电荷探测器，以制造固体或软材料表面的电势的纳米级分辨率图。 将使用基于最敏感的电荷检测器的高速版本单电子晶体管（SET）的新型传感器。该传感器采用集合和射频反射仪的阵列，以在微秒时间范围内提供有关快速充电过程的信息。 该技术的功能使无法使用表面电位的传统测量进行实验。 例如，在现有测量值中，扫描探针会打扰正在测量的表面，因此很难测量仅限制在表面区域的电子等电荷（例如电子）。 相比之下，该项目中进行的测量对表面的破坏性将少得多，从而可以观察到现象，例如电子的wigner定位。 该项目还涉及一项外展计划，该计划将通过涉及教职员工和研究生的课堂活动，以及将学生带到巴黎圣母院实验室的课堂活动，以推广计划为目标。这些活动将每年与50至100名学生联系。中学年龄的儿童是宣传的出色团体，因为他们已经足够了解科学，但仍在选择他们的兴趣领域。 South Bend公立学校的学生人数多样化，来自科学技术领域中人数不足的团体的大量学生。该项目将使用与扫描的探针系统耦合的超敏感电器，以映射材料表面的潜在。 在表面电势测量中，两种方法占主导地位：开尔文探针力显微镜（KPFM）和静电力显微镜（EFM）。开尔文探针是最流行的技术，因为它可以对接触电势差（CPD）产生定量测量，而EFM只能测量CPD的定性变化。该项目设计并制造扫描单电子晶体管探针（S-SETS），并使用它们来表征半导体表面的表面电荷和潜力。 S-SET探针将使用射频反射仪来启用高电荷和潜在灵敏度以及高空间和时间分辨率的CPD测量。集合阵列将用于提供对随机背景电荷波动的改善的免疫力，并为RF电路提供改进的匹配，从而消除了对复杂的共振网络的需求。 此外，使用RF组将使尚未在文献中报道的开尔文力量测量，而这种测量将比传统KPFM的侵入性不如侵入性。 使用扫描的探针系统，可以表征包括半导体和绝缘体在内的各种表面。 特别是，该系统将用于研究半导体量子点中电子的Wigner定位。