GaN:Pr3+ nanostructures for red solid state light emission

Abstract

The photoluminescence of praseodymium implanted and annealed GaN films, quantum wells, nanowires and quantum dots was studied. After implantation and annealing, Pr³⁺ intra-shell luminescence was achieved for all the analysed samples. In the trivalent charge state the ions' luminescence was found to be dominated by the red lines of the ³P₀ → ³F₂ transition. In the case of GaN films, an intense red emission is observed with the naked eye at room temperature. Photoluminescence excitation indicates that the preferential population mechanisms of this emission are achieved by using excitation above the GaN band gap. A correlation of the optically active ions' luminescence spectral shape and peak position in the different structures is established. For the GaN nanowires the ³P₀ → ³F₂ lines of the Pr³⁺ ions are in good agreement with those identified in GaN films. In the case of GaN quantum dots, the ions' emission was found to be similar to that observed in AlN layers. For AlN/GaN/AlN quantum wells a similar behaviour was identified with the sharp ionic luminescence lines superimposed as a broad band, likely generated by the overlap of multiple Pr-centres. The ionic luminescence stability was analysed and discussed for all the studied samples.