Growth of ZrB_2 Single Crystals for Substrates for GaN

GaN衬底ZrB_2单晶的生长

• 批准号: 15550177
• 负责人: OTANI Shigeki
• 金额: $ 2.3万
• 依托单位: National Institute for Materials Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15550177/
• 关键词: Gallium nitride; substrate; Zirconium diboride; single crystal; ニホウ化ジルコニウム

ZrB_2 has almost the same lattice constant and thermal expansion coefficient as those of gallium nitride, GaN, and further high thermal and electric conductivity. High quality GaN films with dislocation density of less than 10^7 /cm^2 were grown on the substrates of ZrB_2 crystals, which were prepared by the floating zone method because of high melting point, 3220℃. Therefore, in this research, improvement in the purity and quality of ZrB_2 crystals was tried for the practical use.The crystals prepared from the commercial powders, often cause some troubles because of the low purity, <99%. The main impurities are iron, carbon and so on. For example, carbon impurity in the crystal precipitates on the surface due to heating in vacuum. Therefore, in order to improve the purity, the starting material was synthesized by reaction of zirconia and boron, ZrO_2 + 4B. The contents of iron and carbon decreased to 30 ppm, respectively. They further decreased to 4 ppm and less than 20 ppm, respectively, due to the floating zone growth. The total purity of the crystal increased to >99.99%, high enough to suppress the above problems.Factors which determine the crystal quality were examined by comparison with the other diboride crystals, TiB_2, HfB_2, VB_2, NbB_2, TaB_2 and CrB_2. The etch pit densities decreased with decreasing the growth temperature. In the case of ZrB_2, the etch pit density was 5 x 10^6 /cm^2, which would decrease to half, decreasing the growth temperature by 200℃. The formation of the sub grain boundaries and cracks were influenced by the anisotropy of the thermal expansion. ZrB_2 crystals with the highest quality among the diborides had the small thermal expansion coefficients and the small anisothoropy. Therefore, to improve the crystal quality further, it was found to be important to find a flux which decreases the growth temperature.

与氮化炮，GAN和进一步的高热和电气高质量的晶格呈晶状体和热膨胀相同。由浮动区方法元件制备的，因为高熔点为3220°C。Zrb_2晶体的纯度和质量被尝试用于实践。杂质，碳等等。到30 ppm，由于浮动区的生长，它们进一步降低到4 ppm，而尊敬的人少于20 ppm。通过与其他Diboride晶体，TIB_2，HFB_2，VB_2，NBB_2，TAB_2，TAB_2和CRB_2进行比较，对ITY进行了检查。亚晶界和裂纹是热膨胀的不属性。

项目成果

実験化学講座23 無機化合物(5. 10 ホウ化物)

实验化学课程23无机化合物（5. 10硼化物）

• 发表时间: 2005
• 作者: 大谷茂樹;森孝雄
• 通讯作者: 森孝雄

Theoretical study of the electronic structure of HfB2(0001)-X (X=Li-Ne) surf

HfB2(0001)-X(X=Li-Ne)表面电子结构的理论研究

• 发表时间: 2004
• 期刊: J. Physical Chemistry 108
• 作者: W.Hayami;T.Aizawa;T.Tanaka;S.Otani
• 通讯作者: S.Otani

Surface core-level shift and electronic structure of transition metal diboride (0001) surfaces

过渡金属二硼化物(0001)表面的表面核能级位移和电子结构

• 发表时间: 2005
• 期刊: Physical Review B 71
• 作者: T.Aizawa;S.Suehara;S.Hishita;S.Otani;M.Arai
• 通讯作者: M.Arai

Surface core-level shift and electronic structure of transition-metal diboride(0001)surfaces

过渡金属二硼化物(0001)表面的表面核能级位移和电子结构

• 发表时间: 2005
• 期刊: Physical Review B (In Press)
• 作者: 相沢俊;末原茂;菱田俊一;大谷茂樹;新井正男
• 通讯作者: 新井正男

S.Otani, T.Mori: "Flux growth of CaB6 crystals"J.Materials Science Letters. 22. 1065-1066 (2003)

S.Otani、T.Mori：“CaB6 晶体的助熔剂生长”J.材料科学快报。