研究目的
Investigating the nucleation of three-dimensional Ge islands on a pre-patterned Si substrate with an array of round pits and the influence of pit shape on the spatial arrangement of these islands.
研究成果
The shape of the bottom of nucleation regions (pits) influences the formation of Ge nanoislands on the Si(100) surface. Ge islands nucleate inside pits with pointed bottoms and along the perimeters of pits with flat bottoms. This is due to variations in the distribution of elastic strains during the growth of the Ge wetting layer.
研究不足
The linear dimensions of the model structures in the simulation were about an order of magnitude smaller than the dimensions in the experiment, which might affect the accuracy of the strain distribution representation.
1：Experimental Design and Method Selection:
The study involved the use of electron-beam lithography (EBL) and plasma chemical etching (PCE) to create a patterned Si(100) surface with an array of round pits. Germanium was deposited onto the patterned Si(100) substrate using molecular-beam epitaxy (MBE). The nucleation of 3D Ge islands was studied under different pit shapes.
2：Sample Selection and Data Sources:
Patterned Si(100) substrates with pits of different shapes (inverted triangles with sharp vertices and trapeziums with flat bottoms) were used. The morphology was studied by atomic-force microscopy (AFM) and scanning electron microscopy (SEM).
3：List of Experimental Equipment and Materials:
SIVA-21 (Riber) setup for MBE, Solver PRO (NT-MDT) AFM microscope, SEM equipment of the CKP “Nanostructury”.
4：Experimental Procedures and Operational Workflow:
The substrate was chemically treated and coated with a protective oxide layer, which was then removed in the MBE setup. A Si buffer layer was deposited, followed by Ge deposition. The morphology of the substrates and structures was then analyzed.
5：Data Analysis Methods:
The distribution of elastic energy in the Ge layer was calculated using Monte Carlo (MC) simulation to interpret the experimental results.
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