Presenter: Chad M. Parish
Advisor(s): Dr. Phil Russell
Author(s): Chad M. Parish, Curt L. Progl, and Dr. Phillip E. Russell
Graduate Program: Materials Science and Engineering
Title: Development and Implementation of Electron Microscopic Techniques for Characterization of Nitride-based Semiconductors
Abstract: Gallium Nitride (GaN) and its alloys are wide-gap semiconductors used in the manufacture of green-to-ultraviolet range light-emitting diodes (LEDs) and high-power electronics. Commercially-grown GaN is deposited on lattice-mismatched substrates such as sapphire or 6H-SiC, and therefore has a high density of defects. Standard characterization techniques will not elucidate the electronic and optical properties of these defects. Techniques such as electron beam induced current (EBIC) and cathodoluminescence (CL) are necessary to examine the optoelectronic activity of defects in these semiconductor devices at the nanoscale. We have developed experimental apparatus for the application of EBIC and CL techniques to GaN-based LEDs, and implemented them into scanning electron microscopes, and are extending our development into a scanning transmission electron microscope. We have also developed careful and repeatable sample-preparation procedures, using standard metallographic practices and a focused ion beam tool. Details of these developments will be discussed. Applications of these techniques to GaN-based LEDs, and knowledge gained, is also presented. Finally, results of computational modeling that confirm and explain these results are given.