Photoluminescence and cathodoluminescence analyses of GaN powder doped with Eu

Abstract

A high yield process to produce gallium nitride (GaN) powder doped with europium (Eu) is presented. Eu is in situ incorporated into GaN powder through the reaction between a molten alloy of Ga and Eu along with NH3 at 1000 °C using Bi as a wetting agent. This procedure provides a method to produce a GaN:Eu phosphor with high yield and low cost. Room temperature photoluminescence (PL) measurements are studied on GaN:Eu powders with different Eu concentrations. The maximum PL intensity is obtained at a Eu concentration of 1.25 at. %. Cathodoluminescence spectra at room temperature exhibit many detailed transitions in the 530–630 nm range.

High intensity red emission from Eu doped GaN powders

“…Up to now, the few reported work on Eu doped GaN powders include a combustion method [3]; ammonolysis of the freeze-dried [4]; and a two-stage vapor phase method [5], etc. Recently, we developed a simple, low-cost, and high-yield process to convert Ga to high quality GaN using Bi as a wetting agent, and Er, Eu doping has been achieved [7,8,10]. In this paper, we report the effect of the growth temperature on the effective incorporation of Eu in GaN powders.…”

“…Though doping of Eu, Er, Tm and other RE elements in GaN either in-situ or by implantation has been achieved by several groups [2], GaN in most cases is in the form of films produced by MBE, CVD or sputtering, etc. There exists much less work exists on rare earth doped GaN powders [3][4][5][6][7][8].…”

“…After purging the tube with high purity Ar, the temperature was brought up and the gas switched to 99.9999% NH 3 for reaction. This process was described in detail elsewhere [8,10]. After 5 hours of reaction, the layered chunk product was taken out and ground into fine powders with particle size ~3 µm as observed by SEM.…”

“…After 5 hours of reaction, the layered chunk product was taken out and ground into fine powders with particle size ~3 µm as observed by SEM. Any residual Bi can be removed by annealing at 1020 °C for a few hours under flowing NH 3 , since at this temperature, the Bi equilibrium vapor pressure is ~10 3 and ~10 6 times higher than that of Ga and Eu respectively, and much higher than the metal vapor pressure above their nitrides [8]. The samples were then characterized with photoluminescence (PL), X-ray diffraction (XRD) and Raman spectroscopy.…”

Luminescence spectroscopy of Eu‐implanted zincblende GaN

“…Recently, Park and Steckl reported that two different Eu 3+ sites are involved in stimulated emission (lasing) in W-GaN:Eu optical cavities [5]. A reported blue-shift of the dominant Eu 3+ peak in W-GaN powder, to 611 nm, ascribed to the existence of stacking faults and cubic structures [6], was not reproduced in later work [7]; moreover, aggregation of nanocrystalline powder into micrometer-sized conglomerates reportedly causes a significant red-shift of Eu 3+ emission spectra [8]. Despite many investigations, the luminescence spectroscopy of RE-doped GaN and the energy transfer from the wide bandgap host to the optically active RE centres are not well understood.…”