Abstract
Ge/Si heterostructure with fully strain-relaxed Ge film was grown on a Si (001) substrate by using a two-step process by ultra-high vacuum chemical vapor deposition. The dislocations in the Ge/Si heterostructure were experimentally investigated by high-resolution transmission electron microscopy (HRTEM). The dislocations at the Ge/Si interface were identified to be 90° full-edge dislocations, which are the most efficient way for obtaining a fully relaxed Ge film. The only defect found in the Ge epitaxial film was a 60° dislocation. The nanoscale strain field of the dislocations was mapped by geometric phase analysis technique from the HRTEM image. The strain field around the edge component of the 60° dislocation core was compared with those of the Peierls–Nabarro and Foreman dislocation models. Comparison results show that the Foreman model with a = 1.5 can describe appropriately the strain field around the edge component of a 60° dislocation core in a relaxed Ge film on a Si substrate.
Highlights
Dislocation, which is a classic topic in material science because of its significance in the mechanical property of materials, has received considerable attention from researchers [1,2,3]
This paper aims to identify the type of dislocations in Ge/Si heterostructures and to verify experimentally the currently available dislocation models
Ge Epitaxial Film Preparation A custom-designed ultra-high vacuum chemical vapor deposition system equipped with pyrolytic BN effusion cells was used to grow Ge on a Si(001) substrate
Summary
Dislocation, which is a classic topic in material science because of its significance in the mechanical property of materials, has received considerable attention from researchers [1,2,3]. Aside from mechanical properties, the electrical properties of materials, including their electrical conductivity and electron mobility, are affected by the deformation fields of dislocations in semiconductors such as Ge [4]. A method combining high-resolution transmission electron microscopy (HRTEM) and geometric phase analysis (GPA) has shown to be an effective method for mapping strain fields at the nanoscale. GPA [6] is an image processing technique that has been used in a wide variety of systems, including Si heterostructures [7], nanoparticles [8], crack tips [9], and so on. Numerical Moirecan be calculated from the geometric phase of the GPA. By selecting a geometric phase image, a desired numerical Moireimage that corresponds to a group of special crystal planes can be obtained, allowing a detailed analysis of this group of crystal planes [10]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
