Low temperature growth of GaN single crystals using a Na metal flux

Wurtzite-type GaN single crystals were obtained at 650 - 840℃for 72 - 300 h in a sealedstainless-steel tube container, using GaNaN - D23 and Na as starting materials. GaN formation finished within 24h at 840℃。In thesamples heated at lower temperatures for 24h, Ga-Na intermetallic compoundGa - D239 - D2Na - D222 - D2, covered with a GaN layerprecipitated at the bottom of the stainless-steel tube. Longer reaction time was needed toaccomplish the nitridation of Ga at these conditions.The GaN single crystals deposited in theregion of 2cm from the bottom of the stainless-steel tube container. the GaN single crystals grownin the upper half part of the region platelet with amber color or colorless. the maximum sizeof the crystals is about 2mm .他们的grew perpendicular to the tube wall. In the lower part，the crystals dark yellow and pyramidal or prismatic，having a size of 0.4 - 0.7 mm. The pressure of N - D22 - D2 in The sealed stainless-steel tubecontainer decreased during the formation of GaN. the morphology change suggested that the N D22 - D2pressure approached an equilibrium partial pressure of N - 22 - D2 for GaN formation.Electronmicroprobe analysis did not detect any impurity elements in the crystals. the near band-edgeemission of GaN was observed at 363 mm by cathodoluminescence spectroscopy. The colorlesstransparent platelet single crystals prepared at 650℃for 300h exhibited the sharpest peak withstrongest intensity. This revealed that the crystals with a good quality grew at lower temperatureand a slow growth rate。

Wurtzite-type hexagonal GaN single crystals were obtained at 650 - 840℃ for 72 - 300 h in a sealed stainless-steel tube container, using Ga, NaNィイD23ィエD2 and Na as starting materials. GaN formation finished within 24 h at 840℃. In the samples heated at lower temperatures for 24 h, Ga-Na intermetallic compound, GaィイD239ィエD2NaィイD222ィエD2, covered with a GaN layer, precipitated at the bottom of the stainless-steel tube. Longer reaction time was needed to accomplish the nitridation of Ga at these conditions.The GaN single crystals were deposited in the region of 2 cm from the bottom of the stainless-steel tube container. The GaN single crystals grown in the upper half part of the region were platelet with amber color or colorless. The maximum size of the crystals is about 2 mm. They grew perpendicular to the tube wall. In the lower part, the crystals were dark yellow and pyramidal or prismatic, having a size of 0.4 - 0.7 mm. The pressure of NィイD22ィエD2 in the sealed stainless-steel tube container decreased during the formation of GaN. The morphology change suggested that the NィイD22ィエD2 pressure approached an equilibrium partial pressure of NィイD22ィエD2 for GaN formation.Electron microprobe analysis did not detect any impurity elements in the crystals. The near band-edge emission of GaN was observed at 363 mm by cathodoluminescence spectroscopy. The colorless transparent platelet single crystals prepared at 650℃ for 300 h exhibited the sharpest peak with strongest intensity. This revealed that the crystals with a good quality grew at lower temperature and at a slow growth rate.