Xu Buqing, Du Yong, Wang Guilei, Xiong Wenjuan, Kong Zhenzhen, Zhao Xuewei, Miao Yuanhao, Wang Yijie, Lin Hongxiao, Su Jiale, Li Ben, Wu Yuanyuan, Radamson Henry H
Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China.
School of Integrated Circuits, University of Chinese Academy of Sciences, Beijing 100029, China.
Materials (Basel). 2022 May 18;15(10):3594. doi: 10.3390/ma15103594.
In this manuscript, a novel dual-step selective epitaxy growth (SEG) of Ge was proposed to significantly decrease the defect density and to create fully strained relaxed Ge on a Si substrate. With the single-step SEG of Ge, the threading defect density (TDD) was successfully decreased from 2.9 × 10 cm in a globally grown Ge layer to 3.2 × 10 cm for a single-step SEG and to 2.84 × 10 cm for the dual-step SEG of the Ge layer. This means that by introducing a single SEG step, the defect density could be reduced by two orders of magnitude, but this reduction could be further decreased by only 11.3% by introducing the second SEG step. The final root mean square (RMS) of the surface roughness was 0.64 nm. The strain has also been modulated along the cross-section of the sample. Tensile strain appears in the first global Ge layer, compressive strain in the single-step Ge layer and fully strain relaxation in the dual-step Ge layer. The material characterization was locally performed at different points by high resolution transmission electron microscopy, while it was globally performed by high resolution X-ray diffraction and photoluminescence.
在本论文中，提出了一种新颖的锗双步选择性外延生长（SEG）方法，以显著降低缺陷密度，并在硅衬底上制备出完全应变弛豫的锗。采用锗的单步SEG时，位错缺陷密度（TDD）成功地从整体生长的锗层中的2.9×10⁶/cm²降低到单步SEG时的3.2×10⁵/cm²，锗层双步SEG时降低到2.84×10⁵/cm²。这意味着通过引入单步SEG，缺陷密度可降低两个数量级，但通过引入第二步SEG，这种降低幅度仅进一步降低了11.3%。表面粗糙度的最终均方根（RMS）为0.64nm。应变也沿样品横截面进行了调制。在第一层整体锗层中出现拉伸应变，在单步锗层中出现压缩应变，在双步锗层中实现完全应变弛豫。通过高分辨率透射电子显微镜在不同点进行局部材料表征，同时通过高分辨率X射线衍射和光致发光进行整体表征。
