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

Wurtzite型六角GaN单晶体在72 - 300小时密封不锈钢管集装箱中为650 - 840℃，使用Ga、NaN-I-D23-I-D2和Na作为起始材料。GaN在840℃时在24小时内形成。在较低温度下24小时加热的样本中， Ga-Na金属化合物、Ga-Na-D2 Na-D222-D2，覆盖有GaN层，在不锈钢管底部被预先放置。需要更长的反应时间来完成Ga在这些条件下的硝化作用。GaN单晶体存放在不锈钢管容器底部2厘米的区域内。GaN单晶体生长在该地区的上半部分的平板上，有琥珀色或无颜色。晶体的最大尺寸约为2毫米，它们长成永久性的管子壁。在较低的部分，晶体是深色的、黄色的、金字塔形的或棱镜的，尺寸为0.4 - 0.7毫米。密封不锈钢管容器中的压力在GaN形成时被降解。适用于GaN的morphology change suggested that the N-D22-D2 pressure approached an equilibrium partial pressure of N-D22-D2 for GaN。Electron microprobe analysis did not detect any impurity elements in the crystals。GaN的近波段边缘发射被观测到在363毫米处。无色透明平台单晶体准备在650 ° C，以最强的强度展示了300小时的最锐利峰。这篇文章揭示了水晶具有良好的质量，绿色在较低的温度和较低的生长率。

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.