Fabrication and EL emission of ZnO-based heterojunction light-emitting devices

Nitrogen-doped p-type MgZnO films were successfully realized on a-plane sapphire substrates and were used in an n-MgyZn1-yO/n-Zn1-xCdxO/p-MgyZn1-yO:N/p-SiC heterojunction structure to act as barrier layer leading to sharpening of the electroluminescence (EL) in terms of reducing the full width at half maximum (FWHM). The X-ray photoelectron spectroscopy (XPS) analysis of the c-axis-oriented nitrogen-doped MgZnO film confirmed the presence of Mg2+ at 49.8 eV in Mg (2p region) in the ZnO:N lattice, replacing Zn2+. Zn-N formations were clearly visible in the Zn (2p(3/2)) region and the signal for nitrogen-replacing oxygen (No) emerged at 396.9 eV. With respect to ZnO:N polar films (n-type in as-grown conditions), as-grown polar MgZnO:N films had the upper hand by holding a p-type nature due to Mg incorporation ascribed to the formation of Mg-related (interactions of Mg with N) tri-atomic acceptor-donor-acceptor-configured p-type supportive complexes. The nitride formations were noticeable in the X-ray diffraction (XRD) spectra. The formation of complexes and their effects are discussed in this paper.