Seeing the Very Small: Imaging and Solid-State Device Engineering at the Nanoscale

Abstract

The science and engineering of materials and device structures at the nanometer scale have become central themes in fields ranging from solid-state electronics and photonics to the biological sciences. As a result, the characterization, understanding, and control of material and device properties at the nanometer to atomic scale have emerged as essential aspects of materials and device engineering. We will discuss some recent results from our laboratory directed towards the imaging, analysis, and application of nanoscale phenomena in variety of solid-state m aterials and devices. In the area of III-nitride semiconductor heterostructures and devices, we show how scanned probe imaging of electronic structure in InGaN/GaN quantum-well heterostructures reveals nanoscale variations in carrier accumulation behavior associated with monolayer thickness fluctuations and the presence of nanoscale In-rich clusters within InGaN quantum wells. These variations can be correlated with, and explain, differences in luminescence intensity among various nitride-based light emitting diode structures. In the area of high-efficiency photovoltaics, we discuss approaches for design and fabrication of quantum-well solar cells that exploit plasmonic effects and light scattering by metal and dielectric nanostructures integrated with the semiconductor device structure. We show that these approaches lead to substantial improvements in power conversion efficiency with the potential to enable realization of extremely thin, highly efficient solar cells and related devices.

Speaker Biography

Edward Yu received his A.B. (summa cum laude) and A.M. degrees in Physics from Harvard University in 1986, and his Ph.D. degree in Applied Physics from the California Institute of Technology in 1991. Following a one-year postdoctoral appointment at the IBM Thomas J. Watson Research Center in Yorktown Heights, NY, he joined the faculty of the University of California, San Diego, where he is currently Professor of Electrical and Computer Engineering. Current research interests in his laboratory include photovoltaics and other technologies for energy generation; III-nitride semiconductors for electronics and optoelectronics; semiconductor nanowires and other solid-state nanostructures; and nanoscale imaging and characterization techniques. The results of his research have been reported in over 120 archival journal publications. He has served as General and Program Chair of the TMS Electronic Materials Conference (EMC), and of the AVS Nanometer-Scale Science and Technology Division. He is a current member of the DARPA Defense Sciences Research Council (DSRC) and an alumnus (2000-01) of the Defense Sciences Study Group (DSSG). He has been the recipient of an Alfred P. Sloan Research Fellowship, ONR Young Investigator Award, NSF CAREER Award, and UCSD ECE Graduate Teaching Award.