Sheverdyaeva P M, Hogan C, Sgarlata A, Fazi L, Fanfoni M, Persichetti L, Moras P, Balzarotti A
Istituto di Struttura della Materia-CNR (ISM-CNR), S.S. 14, km 163.5, I-34149, Trieste, Italy.
J Phys Condens Matter. 2018 Nov 21;30(46):465502. doi: 10.1088/1361-648X/aae66f. Epub 2018 Oct 25.
We present a joint experimental and theoretical study of the electronic properties of the rebonded-step reconstructed Ge/Si(1 0 5) surface which is the main strained face found on Ge/Si(0 0 1) quantum dots and is considered a prototypical model system for surface strain relaxation in heteroepitaxial growth. Using a vicinal surface as a model system for obtaining a stable single-domain film structure with large terraces and rebonded-step surface termination, we realized an extended and ordered Ge/Si planar hetero-junction suitable for direct study with angle-resolved photoemission spectroscopy. At the coverage of four Ge monolayers photoemission spectroscopy reveals the presence of 2D surface and film bands displaying energy-momentum dispersion compatible with the 5 × 4 periodicity of the system. The good agreement between experiment and first-principles electronic structure calculations confirms the validity of the rebonded-step structural model. The direct observation of surface features within 1 eV below the valence band maximum corroborates previously reported analysis of the electronic and optical behavior of the Ge/Si hetero-interface.
我们对再键合台阶重构的Ge/Si(1 0 5)表面的电子性质进行了实验与理论相结合的研究，该表面是在Ge/Si(0 0 1)量子点上发现的主要应变面，被认为是异质外延生长中表面应变弛豫的典型模型系统。我们使用一个近邻表面作为模型系统，以获得具有大平台和再键合台阶表面终止的稳定单畴薄膜结构，实现了一个适合用角分辨光电子能谱直接研究的扩展且有序的Ge/Si平面异质结。在四个Ge单层的覆盖度下，光电子能谱揭示了二维表面和薄膜能带的存在，其能量 - 动量色散与系统的5×4周期性相匹配。实验与第一性原理电子结构计算之间的良好一致性证实了再键合台阶结构模型的有效性。对价带最大值以下1 eV范围内表面特征的直接观测，证实了先前报道的对Ge/Si异质界面电子和光学行为的分析。
