Formation of aligned CrN nanoclusters in Cr-delta-doped GaN

Cr-delta-doped GaN layers were grown by radio-frequency plasma-assisted molecular-beam epitaxy on GaN template substrates. Cr flux was supplied without nitrogen flow during Cr-delta-doping. Cr incorporation into a narrow thin layer region was confirmed with the depth profile measured by secondary ion mass spectrometry. Structural properties and Cr atom alignments were studied with transmission electron microscopy. It was found that Cr-delta-doped GaN layers were coherently grown with Cr or CrGa nanoclusters in the delta-doped region for low temperature growth (350, 500 °C). It was also found that aligned CrN nanoclusters (approximately 5 nm vertical thickness) with NaCl-type structure were formed in the delta-doped region for the growth at 700 °C.