IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Tuesday Sessions
       Session SC-TuM

Invited Paper SC-TuM1
Nanometer-scale Studies of Possible Dislocation Charging at GaN Interfaces

Tuesday, October 30, 2001, 8:20 am, Room 124

Session: Semiconductor Interfaces and Thin Films
Presenter: J.P. Pelz, The Ohio State University
Authors: J.P. Pelz, The Ohio State University
H.-J. Im, The Ohio State University
Y. Ding, The Ohio State University
E.R. Heller, The Ohio State University
B. Heying, University of California, Santa Barbara
J.S. Speck, University of California, Santa Barbara
W.J. Choyke, University of Pittsburgh
Correspondent: Click to Email
Threading dislocations (TDs) in III-Nitride films are thought to be electrically active and of major concern for device applications. Several recent studies of GaN and AlGaN/GaN films suggested that TDs might develop significant fixed negative charge (up to 1 e- every c-axis lattice spacing) at or near the TD core. We have quantified possible dislocation charging near metal/GaN interfaces using ultra high vacuum Ballistic Electron Emission Microscopy (BEEM) measurements of identifiable TDs, which were compared with electrostatic modeling of conduction band (CB) bending due to fixed local negative charge. Surprisingly, measurements of TDs in GaN films (grown by molecular beam epitaxy (MBE) under Ga droplet conditions) do not indicate any negative charge at TDs close to the metal-GaN interface, with an estimated upper limit of ~0.25 (e-)/c along the TDs. In contrast, we generally observe a mild decrease in the local CB at TDs as well as at step edges, which may be due to piezoelectric surface charge induced by local stress variations. We will discuss on-going measurements of near-interface dislocation charging of III-Nitride films grown under different conditions (MBE Ga-poor, MOCVD, etc.) to investigate how growth conditions affect local dislocation charging and local transport behavior. Time permitting, we will also discuss on-going measurements of how the Schottky Barrier height on metal/SiC contacts depends on SiC polytype, interface orientation, and deposited metal. This work was supported by the Office of Naval Research.