AVS 47th International Symposium
    Semiconductors Monday Sessions
       Session SC2+EL+SS-MoM

Paper SC2+EL+SS-MoM7
Enhanced Thermal Stability of Au Film on GaN by Thin Cr Interfacial Layer

Monday, October 2, 2000, 10:20 am, Room 312

Session: Dissimilar Materials
Presenter: J.H. Kim, Chungbuk National University, Korea
Authors: J.H. Kim, Chungbuk National University, Korea
H.J. Kang, Chungbuk National University, Korea
C.Y. Kim, LG CIT, Korea
J.M. Seo, Chonbuk National University, Korea
Correspondent: Click to Email
In order to enhance the thermal stability of Au film on GaN, 4 ML of thin Cr layer had been deposited prior to Au evaporation. The AFM image shows that, upon postannealing at 650C, Au overlayer with Cr interlayer still keeps its uniformity without forming either pits or islands, while the same amount of Au without Cr interlayer is agglomerated. The corresponding results of scanning Auger microscopy combined with the high resolution x-ray photoelectron spectroscopy indicate that the interfacial Cr partially mixes with GaN and partially mixes with Au overlayer, and reduces the Schottky barrier height of p-type GaN by 0.4 eV. The core level analyses of Cr 2p, Au 4f and Ga 2p indicate a small portion of Ga species also segregates to the top side of this AuCr alloy overlayer. It has been concluded that the role of Cr interlayer for enhancing thermal stability of Au overlayer is in the gradual relaxation of the strain originating from thermal-expansion-coefficient-difference through diffusing into both sides without losing N species.