LOW-TEMPERATURE GROWTH OF 3C-SIC FILMS ON SI SUBSTRATE

由于3C-SiC与Si之间的晶格失配约为20%，热膨胀系数相差约8%，以及在高于1000℃的高温下Si衬底的损耗，在Si衬底上生长的立方碳化硅（3C-SiC）的质量非常差。为了帮助克服这些问题，在SiC生长之前，通过衬底的碳化和SiC靶的溅射在Si衬底的表面上制备SiC缓冲层。SiC缓冲层可以防止衬底的损耗，但不能完全解决Si和SiC之间的晶格失配和热膨胀系数的差异，近年来，C与Si和Si_ Ge_x的合金化<1-x>由于能够控制与Si晶格失配相关的应变而引起人们的关注。C、Si和Ge之间的共价半径、键长和键强度存在很大差异。因此，可以释放菌株 关于我们 如果在SiC生长之前先制备Ge_ C_x层，则由于SiC/Si界面原子自组织互扩散引起的晶格失配，会导致SiC/Si界面的晶格<1-x>失配。例如，C向Si中的扩散和Ge向SiC中的扩散可能导致SiC和Si之间的晶格失配的减小。在<1-0.63><0.63>600℃下在Si衬底上制备了厚度为5 nm的Ge_ C_4缓冲层，并在相同温度下氢气气氛中退火30 min，在850℃下可以在有缓冲层的Si衬底上生长3C-SiC薄膜，3C-SiC薄膜的结晶度与缓冲层的厚度密切相关。观察到3C-SiC膜在约5 nm的缓冲厚度处的最大X射线衍射强度。SiC薄膜结晶度的提高与SiC/Si界面应变在SiC薄膜生长过程中在缓冲层中的释放有关，Si（001）衬底对SiC薄膜外延生长的影响在缓冲层中得到缓解。SiC晶粒“自由”生长，即其生长不受Si衬底的影响。SiC晶粒的取向取决于SiC晶粒成核和生长的自由能。因此，（111）取向的SiC晶核在低温下的自由能较小，有利于（111）取向的SiC晶粒在薄膜中生长。少

The quality of the cubic silicon carbide (3C-SiC) grown on a Si substrate was very poor due to the large lattice mismatch of about 20 % between 3C-SiC and Si, the relatively large difference in thermal expansion coefficients of about 8 %, and the loss of the Si substrate at high growth temperatures above 1000℃. To help overcome these problems, a SiC buffer layer was prepared on the surface of a Si substrate by carbonization of the substrate and sputtering of a SiC target before the SiC growth. The SiC buffer layer prevented the loss of the substrate, but did not solve completely the problems of lattice mismatch and difference in thermal expansion coefficients between Si and SiC.Recently, the alloying of C with Si and Si_<1-x>Ge_x has attracted attention because of its ability to control the strain associated with the lattice mismatch to Si. There are large differences in covalent radius, bond length, and bond strength among C, Si and Ge. Therefore, it is possible to release the strains … More due to lattice mismatch at the SiC/Si interface by atomic self-organized interdiffusion if a Ge_<1-x>C_x layer is prepared before the SiC growth. For example, the diffusions of C into Si and Ge into SiC may result in the decrease in lattice mismatch between SiC and Si.In this project, we studied a new growth technique for 3C-SiC on a Si substrate. The Ge_<1-0.63>C_<0.63> buffer layer with a thickness of 5 nm was prepared on the Si substrate at 600℃, and was annealed at the same temperature in hydrogen atmosphere for 30 min. 3C-SiC can be grown on the substrate with the buffer layer at 850℃.The crystallinity of the 3C-SiC film depends strongly on the thickness of the buffer layer. The maximum X-ray diffraction intensity of the 3C-SiC film at a buffer thickness of about 5 nm is observed. The improved crystallinity of the SiC film is related to the release of the SiC/Si interface strains in the buffer layer during the growth of the SiC film.The effects of the Si(001) substrate on epitaxial growth of the SiC film are relaxed in the buffer layer. The SiC grains grow 'freely', that is, its growth is not affected by the Si substrate. The orientation of the SiC grains depends on free energies for nucleation and growth of the SiC grains. Therefore, the (111) oriented SiC grains are preferentially grown in the film because of smaller free energy of the (111)-oriented SiC nuclei at low temperature. Less