GaN Si wafer Cross-Section (image) University of Illinois College of Engineering Share Print E-Mail Caption a) Cross sectional structure. b) TEM image of top 80 nm of the HEMT structure. The dark gray layer marks the start of the surface. c) STEM image of top 80 nm. The surface starts beneath the black layer and the dark band in the image is the AlN spacer. d) EDS Chemical Analysis of top 25 nm. Data before 4 nm are the background values from above the surface. Credit University of Illinois Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.