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单晶Si和蓝宝石 (0 0 0 1)是两种重要的 3C SiC异质外延衬底材料 ,然而 ,由于Si及蓝宝石和 3C SiC之间大的晶格失配度和热膨胀系数失配度 ,在 3C SiC中会产生很大的内应力 ,直接影响 3C SiC的电学特性。Raman散射测试是一个功能很强的测试方法 ,其强度、宽度、Raman位移等有关Raman参数可以给出有关SiC晶体质量的信息 ,其中包括内应力。利用背散射几何构置的Raman方法研究了Si(10 0 )和蓝宝石 (0 0 0 1)衬底上LPCVD方法生长的SiC外延薄膜 ,在生长的所有样品中均观察到了典型的 3C SiC的TO和LO声子峰 ,在3C SiC/Si材料中 ,这两个声子峰分别位于 970 3cm-1和 796 0cm-1,在 3C SiC/蓝宝石材料中 ,分别位于96 5 1cm-1和 80 1 2cm-1,这一结果表明这两种外延材料均为 3C SiC晶型。利用一个 3C SiC自由膜作为无应力标准样品 ,并根据 3C SiC/Si和 3C SiC/蓝宝石的TO和LO声子峰Raman位移相对于自由膜的移动量 ,得到 3C SiC中的内应力约分别为 1GPa和 4GPa。实验发现在这两种材料的TO声子峰的Raman位移移动方向相反 ,通过比较 3C SiC、Si和蓝宝石的热膨胀系数 ,预期Si衬底上的 3C SiC外延膜受到的应力为张应力 ,而蓝宝石衬底上 3C SiC受到的应力则为压应力。
However, due to the large lattice mismatch and mismatch of thermal expansion coefficient between Si and sapphire and 3C SiC, single crystal Si and sapphire (001 001) are two important 3C SiC heteroepitaxial substrate materials. However, In 3C SiC will have a great internal stress, a direct impact on 3C SiC electrical properties. The Raman scattering test is a very powerful test method. The Raman parameters such as intensity, width, Raman shift, etc. give information about the quality of SiC crystals, including internal stress. The SiC epitaxial films grown by LPCVD on Si (100) and sapphire (001) substrates were studied by Raman method with the backscattering geometry. Typical 3C SiC TO samples were observed in all grown samples And LO phonon peaks. These two phonon peaks are located at 970 3 cm-1 and 796 0 cm-1, respectively, in the 3C SiC / Si material and in the 3C SiC / sapphire material at 96 5 1 cm -1 and 80 1, respectively 2cm-1, the results show that both epitaxial materials are 3C SiC crystal form. A 3C SiC free film was used as a stress-free standard sample and the internal stress in 3C SiC was approximately 1GPa and 4GPa. It has been found experimentally that the TO phonon peaks of these two materials have opposite Raman shift directions. By comparing the thermal expansion coefficients of 3C SiC, Si and sapphire, it is expected that the stress applied to the 3C SiC epitaxial film on the Si substrate will be tensile and the sapphire The stress on 3C SiC substrate is compressive stress.