AVS 50th International Symposium
    Semiconductors Wednesday Sessions
       Session SC+EM-WeP

Paper SC+EM-WeP11
Current Mapping of GaN Films

Wednesday, November 5, 2003, 11:00 am, Room Hall A-C

Session: Poster Session
Presenter: J.C. Dickinson, Virginia Commonwealth University
Authors: A.A. Pomarico, University of Lecce, Italy
J.C. Dickinson, Virginia Commonwealth University
R. Cingolani, University of Lecce, Italy
H. Morkoc, Virginia Commonwealth University
A.A. Baski, Virginia Commonwealth University
Correspondent: Click to Email
GaN-based devices have made remarkable advances recently, but still suffer from excessive current leakage, due in part to extended defects in the material and point defects which are not well understood. We have used the technique of conductive atomic force microscopy (C-AFM) to investigate how the local conductivity of GaN films is related to morphology.@footnote 1@ Our studies indicate enhanced conductivity for prismatic planes found around islands on as-grown samples, and on the edges of pits formed by post-growth chemical etching. In the case of etched HVPE samples, AFM images show hexagonal pits produced by the etching of defect sites on c-plane GaN. Simultaneous C-AFM images show detectable current only at the edges of such pits for forward-bias voltages below 4 V. This indicates that crystallographic planes tilted with respect to the c-plane have a significantly higher conductivity than surrounding areas. Although still under investigation, possible mechanisms for this enhanced electrical activity include extended defects, surface states, and modified Schottky barrier heights on prismatic planes. @FootnoteText@@footnote 1@ A.A. Pomarico et al., Appl. Phys. Lett. 82, 1890 (2003).