IMRI Seminar: Imaging Material Properties at the Nanoscale

Abstract: Nanoscale-resolution imaging is the key metrology method that empowers nanotechnology. The atomic force microscope (AFM) is a very unique scientific instrument to explore material properties at the nanoscale. The most important function of an AFM is to image surface topography. Industry has been using this function for failure analysis and quality control. Research interest has been focused on imaging in situ to monitor crystal growth, changes in biological molecules, etc. Using AFM with certain hardware, more materials properties can be obtained. Using scanning capacitance microscopy and scanning microwave impedance microscopy, semiconductor doping profiles can be measured. Material work function can be measured using Kelvin probe force microscopy. Scanning thermal microscopy can measure the thermal conductivity map. Piezo response force microscopy (PFM) gives the piezoelectric coefficient. Magnetic force microscopy characterizes the magnetic field from the sample. Scanning electrochemical microscopy is used to monitor the pA EC current. Huang's research focuses on using AFM for mapping optical near-fields with nanometer resolution, limited mainly by the AFM probe geometry. She profiles the electric field distributions of tightly-focused laser beams with different polarizations, and shows the optical force map between a sharp gold-coated AFM probe and a 15 nm spherical gold nanocrystal under different illumination conditions. The experimentally-recorded force maps agree well with theoretical predictions based on a dipole-dipole interaction model and Comsol simulations.

Bio: Fei Huang has been a senior field Service engineer in the Atomic Force Microscope group of Bruker Corp. since 2017. She has performed extensive installs, trainings and debugs with all the application modules for both industry and academic users, training customers at more than 60 companies and universities. Huang received her Ph.D. in electrical engineering from UCI under the advisement of Prof. Kumar Wickramasinghe for her thesis on photon-induced force microscopy (PiFM). PiFM detects light-induced forces in molecules and materials. Her primary expertise is instrumentation with AFM and optics. Prior to joining UCI, Huang worked as a researcher at Hitachi Research & Development Corp. in China, focusing on digital TV development. She holds a master's degree from the Institute of Acoustics, Chinese Academy of Sciences, and a B.S. from Nankai University, China.

Host: Xiaoqing Pan