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.

A strategy is demonstrated for identifying unambiguously and characterizing quantitatively the effects of distributions of conduction electron concentrations arising from intentional or unintentional dopants in semiconductors by magic-angle spinning (MAS) NMR. The 71Ga MAS NMR spectra of a number of chemically synthesized GaN samples with no intentional doping show inhomogeneously broadened absorptions to high frequency of the main peak. These broad signals are shown, from spin-lattice relaxation time measurements as a function of shift position in a single sample, to be due to Knight shifts arising from degenerate conduction electrons. For a GaN sample with Ge as an intentional dopant at the 0.13% (wt) level, the spectrum is dramatically broadened and shifted to high frequency by up to several hundred parts per million. Analysis of the inhomogeneously broadened line shape yields a quantitative probability density function for electron carrier concentration in the bulk sample that reflects significant compositional heterogeneity due to a variety of possible sources.

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Green light emission has been directly obtained from Er-doped GaN powder. Er is incorporated into GaN powder through the reaction between molten (Ga+Er) and NH3 at 950–1050°C using Bi as a wetting agent. Photoexcitation with an Ar laser results in strong green emissions from two narrow lines at 537 and 558nm, which are identified as Er transitions from the H11∕22 and S3∕24 levels to the I15∕24 ground state. Microprobe analysis reveals that Er atoms are distributed across powder particles.