γ-LiAlO_2晶体的生长及掺镓研究

Study on the Growth of Pure and Ga^(3+) Doped γ-LiAlO_2 Crystals

由于与GaN晶格失配小(约1.4%),γLiAlO2单晶有望成为GaN外延衬底材料。本文首先使用提拉法生长出了尺寸达45×50mm3的γLiAlO2单晶,然后采用Ga2O3作为掺杂剂,仍用提拉法生长出了三种不同掺镓浓度的LiAl1 xGaxO2(x=0.1,0.2,0.3)晶体,并用X射线粉末衍射(XRPD)分别对晶体及坩锅中剩余的熔体的成份进行了表征。结果表明LiAl1 xGaxO2(x=0,0.1,0.2,0.3)晶体归属于γLiAlO2结晶结构,Ga3+离子部分地取代Al3+离子,发生分凝且分凝系数小于1。

γ-LiAlO2 single crystals are anticipated to act as a promising substrate material for the epitaxy of GaN because of the little lattice misfit (about 1.4%) with GaN. Firstly, large-size γ-LiAlO2 single crystal with dimension of φ 45 × 50 mm3 has been grown by Czochralski technique. Then Ga2O3 was used as a dopant. The doping concentrations of trivalent gallium varied from 10% to 30% (in the melt) with respect to the substituted site. Ga3+-doped γ-LiAlO2 crystals were grown also by Czochralski technique. The components of LiAl1-xGaxO2 (x = 0, 0.1, 0.2, 0.3) as-grown crystals and residual melt in the crucibles were characterized using X-ray powder diffraction (XRPD) analysis, respectively. The result shows that LiAl1-xGaxO2 (x = 0, 0.1, 0.2, 0.3) crystals should be assigned to γ-LiAlO2 crystallization structure, and in which Al3+ ions were partly substituted by Ga3+ ions. Segregation of trivalent gallium was occurred and its segregation coefficient is smaller than 1.