We report on the structural properties of Bi thin films grown on (111) Si substrates with a thickness of 22–30 BL. HRXRD and EBSD measurements show that these Bi films are mainly composed of twinning grains in the (0003) direction. The grain size can be as large as tens of microns. From a double-peak (01\(\overline{1}\)4) φ-scan, we found two pairs of twinning phases coexisting with a rotation angle of ~ 3.6°. We proposed a coincidence site lattice model based on preferential close-packed sites for Bi atoms on Si (111) surface to explain the coexistence of the rotation phases in the quasi-van der Waals epitaxy. From the measured lattice constants c and a of our samples, along with the data from the literature, we derived a c–a relation: (c–c₀) = − 2.038(a–a₀), where c₀ and a₀ are the values of bulk Bi. The normalized position of the second basis atom in the unit cell x, in these strained Bi films is found very close to that of bulk Bi, indicating that the strain does not disturb the Peierls distortion of the lattice. The fixed ratio of bilayer thickness to lattice constant c, reveals that the elastic properties of covalent-bonded bilayer dominate those of Bi crystal.

我们报告了在厚度为 22-30 BL 的 (111) Si 衬底上生长的 Bi 薄膜的结构特性。HRXRD和EBSD测量表明这些Bi薄膜主要由(0003)方向的孪生晶粒组成。晶粒尺寸可大至数十微米。从双峰 (01 \(\overline{1}\) 4) φ 扫描中，我们发现两对孪生相共存，旋转角约为 3.6°。我们提出了一种基于 Si (111) 表面 Bi 原子优先密排位点的重合位点晶格模型，以解释准范德华外延中旋转相的共存。根据测量的样品晶格常数 c 和a，以及文献中的数据，我们推导出 ac- a关系：(c-c ₀ ) = − 2.038( a – a ₀ )，其中 c ₀和a ₀为块体 Bi 的值。在这些应变 Bi 薄膜中，晶胞 x 中第二个基本原子的归一化位置与块体 Bi 的位置非常接近，表明应变不会干扰晶格的 Peierls 畸变。双层厚度与晶格常数 c 的固定比率表明，共价键双层的弹性性能主导 Bi 晶体的弹性性能。