Physical chemistry of aluminum oxynitride and its processing

建立了测定AlN-Al_2O_3体系高温反应平衡的实验方法。用四极杆质谱和气相色谱法成功地测定了与aln - al_2o_3 -石墨共存的平衡态N_2-CO气体组成。根据所得结果，测定了1723 ~ 1899 K温度范围内碳热氮化生成AlN反应的标准吉布斯能变化。根据所得结果，导出了298.15 K时AlN的标准吉布斯生成能和第三定律生成焓。用同样的方法测定了γ-氧氮化铝尖晶石在1908 ~ 2023 K温度范围内的热力学稳定性。测定了alon在α-Al_2O_3和AlN的共析分解温度为1903±4 K，并建立了Al-O-N-C体系的化学势图，用*alon缓冲液在蓝宝石表面制备AlN层。利用氧化氮化铝（alon）作为缓冲层，对蓝宝石进行直接氮化，外延形成了一种新的蓝光/紫外光发射衬底AlN薄膜。在蓝宝石上形成的AlN层和AlN层具有如下的晶体学关系：（0001）AlN//(111)alon//(112^^-0)α- al_2o_3。使用沿缓冲液后，蓝宝石衬底与AlN层界面的晶格失配减小了近一半，这主要归因于AlN单晶的生长。

The experimental method for the high-temperature reaction equilibria in the AlN-Al_2O_3 system has been established. The equilibrium N_2-CO gas compositions coexisting with AlN-Al_2O_3-graphite have been successfully measured by quadrupole mass spectrometry and gas chromatography. From the obtained results, the standard Gibbs energy change of the forming reaction of AlN by carbothermal nitridation is determined at temperatures ranging from 1723 to 1899 K. From the obtained result, the standard Gibbs energy of formation of AlN and the third-law enthalpy of formation of AlN at 298.15 K are derived. By using the same method, the thermodynamic stability of γ-aluminum oxynitride spinel, alon, has been determined in the temperature range from 1908 K to 2023 K. The eutectoid decomposition temperature of alon into α-Al_2O_3 and AlN has been evaluated to be 1903 ± 4 K, and the chemical potential diagram of the Al-O-N-C system has been constructed to fabricate an AlN layer on sapphire with*alon buffer. AlN films as a new substrate for blue/UV light emitters have been epitaxialy formed by direct nitridation of sapphire using aluminum oxynitride (alon) as a buffer layer. The alon and AlN layers formed on sapphire have the following crystallographic relation, (0001)AlN//(111)alon//(112^^-0)α-Al_2O_3The lattice mismatch of the interface between sapphire substrate and AlN layer has been reduced almost half by using the along buffer, which significantly attributes to the growth of single crystalline AlN.