TY - JOUR
T1 - A comparative study of blue, green and yellow light emitting diode structures grown by metal organic chemical vapor deposition
AU - Ramaiah, Kodigala Subba
AU - Su, Y. K.
AU - Chang, S. J.
AU - Chen, C. H.
N1 - Funding Information:
We would like to thank National Science Council (NSC) Taipei, for partial financial support. The authors are highly grateful to central facility people for characterization of the samples. We thank Professor I. Bhat and Dr. S. Menezes for fruitful discussions.
PY - 2006/2
Y1 - 2006/2
N2 - The blue, green and yellow light emitting diode (LED) structures have been fabricated by metal organic chemical vapor deposition (MOCVD), and characterized by using different techniques, in order to understand the mechanism between these LEDs. Atomic force microscopy (AFM) analysis revealed that the surface roughness value and density of etch pits were different in the blue, green and yellow LEDs. The threading, misfit dislocations, interfacial dislocations, nano-pipe-like structures and quantum dot-like structures, which determine quality of the structures, were observed by transmission electron microscope (TEM) in the LED structures. The reasons for their formation in the layers are now elucidated. The indium composition, period width such as well and barrier widths were determined by simulating experimental high resolution X-ray diffraction (HRXRD) spectra. The In composition obtained by HRXRD and photoluminescence (PL) measurements for the same LED structure was not one and the same due to several reasons. In fact, the InGaN quantum well emission peaks at 2.667 and 2.544 eV of the blue and green LEDs, respectively showed S-shaped character shift, whereas the quantum well peak at 2.219 eV of yellow LEDs did not show any shift in the PL spectra with decreasing temperature. The blue, green and yellow LEDs showed different activation energies.
AB - The blue, green and yellow light emitting diode (LED) structures have been fabricated by metal organic chemical vapor deposition (MOCVD), and characterized by using different techniques, in order to understand the mechanism between these LEDs. Atomic force microscopy (AFM) analysis revealed that the surface roughness value and density of etch pits were different in the blue, green and yellow LEDs. The threading, misfit dislocations, interfacial dislocations, nano-pipe-like structures and quantum dot-like structures, which determine quality of the structures, were observed by transmission electron microscope (TEM) in the LED structures. The reasons for their formation in the layers are now elucidated. The indium composition, period width such as well and barrier widths were determined by simulating experimental high resolution X-ray diffraction (HRXRD) spectra. The In composition obtained by HRXRD and photoluminescence (PL) measurements for the same LED structure was not one and the same due to several reasons. In fact, the InGaN quantum well emission peaks at 2.667 and 2.544 eV of the blue and green LEDs, respectively showed S-shaped character shift, whereas the quantum well peak at 2.219 eV of yellow LEDs did not show any shift in the PL spectra with decreasing temperature. The blue, green and yellow LEDs showed different activation energies.
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U2 - 10.1016/j.sse.2005.10.028
DO - 10.1016/j.sse.2005.10.028
M3 - Article
AN - SCOPUS:32344437908
SN - 0038-1101
VL - 50
SP - 119
EP - 124
JO - Solid-State Electronics
JF - Solid-State Electronics
IS - 2
ER -