title: Interfacial reactions of nano-structured Cu-doped indium oxide/indium tin oxide ohmic contacts to p-GaN.
abstract: Interfacial microstructure and elemental diffusion of Cu-doped indium oxide (CIO)/indium tin oxide (ITO) ohmic contacts to p-type GaN for light-emitting diodes (LEDs) were investigated using cross-sectional transmission electron microscopy (XTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction. The CIO/ITO contacts gave specific contact resistances of approximately 10(-4) omegacm2 and transmittance greater than 95% at a wavelength of 405 nm when annealed at 630 degrees C for 1 min in air. After annealing at 630 degrees C, multi-component oxides composed of Ga2O3-In2O3, Ga2O3-CuO, and In2O3-CuO formed at the interface between p-GaN and ITO. Formation of multi-component oxides reduced the barrier height between p-GaN and ITO due to their higher work functions than that of ITO, and caused Ga in the GaN to diffuse into the CIO/ITO layer, followed by generation of acceptor-like Ga vacancies near the GaN surface, which lowered contact resistivity of the CIO/ITO contacts to p-GaN after the annealing.
authors.affiliation: Fusion Technology Team, Korea Institute of Ceramic Engineering and Technology, Seoul 153-801, Korea.
authors.forename: Young Joon
authors.initials: YJ
authors.lastname: Yoon
authors.forename: S W
authors.initials: SW
authors.lastname: Chae
authors.forename: B K
authors.initials: BK
authors.lastname: Kim
authors.forename: Min Joo
authors.initials: MJ
authors.lastname: Park
authors.forename: Joon Seop
authors.initials: JS
authors.lastname: Kwak