Radiation response of strained silicon-germanium superlattices /
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis eBook |
| Language: | English |
| Published: |
[College Station, Tex.] :
[Texas A&M University],
[2011]
|
| Subjects: | |
| Online Access: | Link to OAK Trust copy |
| Abstract: | The purpose of this study is to investigate the role of strain in the accumulation of crystalline defects created by ion irradiation. Previous studies state that strained Si1-xGex is more easily amorphized by ion irradiation than unstrained, bulk Si in a periodic superlattice structure; however, the reason for preferential amorphization of the strained Si1-xGex layer in the periodic structure of strained and unstrained layers is not well understood. In this study, various ion irradiations will be carried out on SiGe strained layer superlattices grown on (100)-orientation bulk Si by low temperature molecular beam epitaxy. The samples under investigation are 50 nm surface Si₀.₈Ge₀.₂/bulk Si and 50 nm surface Si/60 nm Si₀.₈Ge₀.₂/bulk Si. Defects will be created in both surface and buried SiGe strained layers by medium and high energy light ion irradiation. The amount of permanently displaced atoms will be quantified by channeling Rutherford backscattering spectrometry. The amorphization model, the path to permanent damage creation, of bulk Si and surface strained SiGe will be investigated. The strain in surface and buried Si₀.₈Ge₀.₂ layers will be measured by comparison to bulk Si with Rutherford backscattering spectrometry by a novel technique, channeling analysis by multi-axial Rutherford backscatter- ing spectrometry, and the limitations of measuring strain by this technique will be explored. Results of this study indicated that the amorphization model, the number of ion collision cascades that must overlap to cause permanent damage, of strained Si₀.₈Ge₀.₂ is similar to that of bulk Si, suggesting that point defect recombination is less efficient in strained Si₀.₈Ge₀.₂. Additionally, a surface strained Si₀.₈Ge₀.₂ is less stable under ion irradiation than buried strained Si₀.₈Ge₀.₂. Repeated analysis by multi-axial channeling Rutherford backscattering spectrometry, which requires high fluence of 2 MeV He ions, proved destructive to the surface strained Si₀.₈Ge₀.₂ layer. |
|---|---|
| Item Description: | "Major Subject: Nuclear Engineering" Title from author supplied metadata (automated record created 2011-08-09 15:09:44). Electronic resource. |
| Physical Description: | 1 online resource. |
| Bibliography: | Includes bibliographical references. |