Near-infrared electroluminescence at room temperature from neodymium-doped gallium nitride thin films

Abstract

Strong near-infrared (NIR) electroluminescence (EL) at room temperature from neodymium (Nd)-doped gallium nitride (GaN) thin films is reported. The Nd-doped GaN films were grown by radio-frequency planar magnetron cosputtering of separate GaN and metallic Nd targets in a pure nitrogen ambient. X-ray diffraction data did not identify the presence of any secondary phases and revealed that the Nd-doped GaN films had a highly textured wurtzite crystal structure with the c-axis normal to the surface of the film. The EL devices were fabricated with a thin-film multilayered structure of Al∕Nd-doped GaN∕Al2O3–TiO2∕indium-tin oxide and tested at room temperate. Three distinct NIR EL emission peaks were observed from the devices at 905, 1082, and 1364nm, arising from the radiative relaxation of the F3∕24 excited-state energy level to the I9∕24, I11∕24, and I13∕24 levels of the Nd3+ ion, respectively. The threshold voltage for all the three emission peaks was ∼150V. The external power efficiency of the fabricated EL devices was ∼1×10−5 measured at 40V above the threshold voltage.