Tomographic HyperSpectral Imaging of (InGa)N Nanopyramid LEDs
Achieving high efficiency light emitting diodes (LED's) is an important aspect of our goal of optimizing energy efficiency in lighting systems. One approach to this problem is the development of III-nitride materials systems, where quantum wells with high InN content create highly efficient LEDs within the green/yellow portion of the visible spectrum. To this end, engineered nano - heterostructures containing Indium were grown selectively by organometallic vapor phase epitaxy on top of GaN films.
The active region of the LEDs which form in this process occur at the apex of nanopyramids. The tomographic hyperspectral imaging in the accompanying movie elucidates the elemental distribution of (In, Ga) N within these complex heterostructures. In this example shown here, one can clearly visualize the outline of the truncated nanopyramid caps which have grown upon the seed GaN nanorods and one can observe that a (In,Ga)N structure preferentially at the apex. Inspection of spectral imaging we see the presence of the solid, coherent (In,Ga)N hexagonal pyramid with a heights of ~ 20 nm forming a quantum dot within each nanopyramid.
Courtesy of: Robert Colby, 1,2, Eric A. Stach,1,2, Nestor J. Zaluzec,3
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47906, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47906, USA
- Electron Microscopy Center, Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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