MSE Seminar: James Hwang, Lehigh University

Description

Scanning Microwave Microscopy for Nanoscale Nondestructive Characterization of Electronic Materials and Live Biological Cells

James C. M. Hwang

Lehigh University, Bethlehem, Pennsylvania 18015, USA

Similar to atomic force microscopy (AFM) or scanning tunneling microscopy (STM), scanning microwave microscopy (SMM) relies on near-field interaction between a scanning stylus and the sample to achieve nanometer resolution despite the centimeter-long wavelength of the microwave signal. However, different from AFM or STM, SMM not only is sensitive to the electromagnetic properties (e.g., electrical conductivity, dielectric constant, and magnetic moment) of the sample, but also can penetrate below the surface up to a micrometer. Compared to other non-contacting techniques such as optical, X-ray or electron microscopy, SMM is highly noninvasive because the energy of microwave photons is on the order of 10 μeV. This makes it feasible to use SMM to sample a live biological cell without affecting its vitality. Although this new characterization technique is still under intense development to make it quantitative, successful examples can already be shown for imaging the nucleus of a live biological cell in its physiological medium, the degradation of two-dimensional atomic-layered material under surface passivation, and the movement of domain walls in ferroelectric and ferromagnetic thin films. New SMM development such as 3D microwave tomography similar to optical coherence tomography is underway, too.

Dr. James Hwang is Professor of ElectricalEngineeringatLehighUniversity.Hegraduatedwith a B.S.degree in Physics from NationalTaiwanUniversity, and M.S.andPh.D.degreesinMaterialsScience from CornellUniversity. After years of industrialexperienceatIBM,Bell Labs,GE,andGAIN, he joinedLehigh in 1988.HecofoundedGAIN and QED;thelatter became a public company(IQE). He is currently a Mary Shepard B. Upson Visiting Professor in Engineering at Cornell University. He has been a visiting professor at Marche Polytechnic University in Italy, NanyangTechnological University in Singapore, National Jiao Tong University in Taiwan, ShanghaiJiaoTongUniversity,EastChinaNormalUniversity,andUniversityofScienceandTechnology in China. He was a Program Officer for GHz-THzElectronics at the US Air Force Office of ScientificResearch from 2011 to 2013.He is a Life Fellow of the InstituteofElectricalandElectronicEngineers.Hehaspublished more than 350refereed technical papers with the impact factor h > 40 according to Google Scholar. He has been granted eight U. S. patents. He has researched on the design, modeling and characterization of electronic, optical and micro-electromechanical (MEM) devices and integrated circuits. His current research interest focuses on scanning microwave microscopy, electromagnetic sensors for individual biological cells, and two-dimensional atomic-layered materials and devices.