Phase separation in InGaN
Quantitative high-resolution transmission electronmicroscopy was used to study the distribution of indium atoms in InxGa1xN alloys by strain mapping. In GaN/InxGa1 xN/GaN quantum wells withx50.1 we find that the sample thickness and the precision to whichdisplacement fields can be extracted from a lattice image determinewhether or not it is possible to discriminate between random alloyfluctuations and cluster formation. In miscible alloys such as SiGe orAlGaN a precision of better than 1 pm is required to reveal randomalloyfluctuations, which presently exceeds experimental capabilities. InInxGa1 xN with x 0.1, a precision of about 3 pm suffices to distinguishrandom alloyfluctuations from indium clusters that are present. ThickInxGa1 xN layers with x 0.6 and x 0.7 show phase separation with awavelength between 2 and 4 nm and a fluctuation amplitude of x 0.10 and0.15, respectively. This produces striped composition fluctuations, whichare modulated by dot-like structures.The similarity of the fluctuationmagnitudes in quantum wells and thick layers suggests that spinodaldecomposition occurs in both materials and our results place the centreof the miscibility gap around x 0.5 0.6.
- Research Organization:
- COLLABORATION - Technische U.Berlin
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 910590
- Report Number(s):
- LBNL--62103; BnR: KC0210010
- Journal Information:
- Philosophical Magazine, Journal Name: Philosophical Magazine Vol. 87; ISSN 0141-8637; ISSN PMABDJ
- Country of Publication:
- United States
- Language:
- English
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