AVS 51st International Symposium
    Semiconductors Tuesday Sessions
       Session SC-TuP

Paper SC-TuP3
Ohmic Contacts to AlGaN

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: M.A. Horsey, The Pennsylvania State University
Authors: S.E. Mohney, The Pennsylvania State University
H.J. Wang, The Pennsylvania State University
M.A. Horsey, The Pennsylvania State University
B.A. Hull, Cree, Inc.
Correspondent: Click to Email
Research on ohmic contacts to Al@sub x@Ga@sub 1-x@N of high Al fraction (x) is presented. The work was motivated by the requirements for low resistance ohmic contacts for short-wavelength devices. In the work on ohmic contacts to n-Al@sub x@Ga@sub 1-x@N with x = 0.6, we have achieved reproducible contact resistivities of 4 x 10@sup -6@ Ohm-cm@sup 2@ with V/Al/V/Au contacts, even without reactive ion etching prior to metallization. These contacts exhibit relatively smooth surface morphologies. We have also investigated the interfacial reactions in these contacts using transmission electron microscopy and Auger electron spectroscopy to provide more information on the mechanism for forming a low resistance ohmic contact. For contacts to p-Al@sub x@Ga@sub 1-x@N (x = 0.45), we have identified annealing conditions required to achieve ohmic contacts, and we discuss the need for passivation of the p-Al@sub x@Ga@sub 1-x@N surface in order to avoid degradation from exposure to light, due we believe to traps at the semiconductor surface. We also describe the relationship between the resistance of the contacts and the interfacial reactions between the contacts and p-Al@sub x@Ga@sub 1-x@N.