| About this Abstract |
| Meeting |
2011 Electronic Materials Conference
|
| Symposium
|
2011 Electronic Materials Conference
|
| Presentation Title |
KK6, Internal Quantum Efficiency in Nanorod LED Arrays Created by Top-Down Techniques |
| Author(s) |
Qiming Li, George Wang, Karl Westlake, Mary Crawford, Stephen Lee, Daniel Koleske, Jeffery Figiel, Karen Cross, Saeed Fathololoumi, Zetian Mi |
| On-Site Speaker (Planned) |
Qiming Li |
| Abstract Scope |
The external quantum efficiency of light-emitting diodes (LEDs) is determined by its internal quantum efficiency (IQE) and light extraction efficiency. The improvement of light extraction efficiency can be dramatically improved by creating additional optical escape routes through texturing the surface of planar LEDs. However, it is not clear that the texturing process, such as plasma etches, will negatively impact the IQE of the devices or not. In this paper, we developed a top-down process for creating nanorod LED arrays from planar LED epitaxial wafers. The IQE of these nanorods was studied and compared to planar LEDs. In the top-down process, we first use a self-assembled monolayer of silica colloids as mask during the plasma etching of MOCVD grown planar LED wafers. We then use a novel anisotropic wet etch technique to remove the plasma etch damage on the sidewall of the nanorod LEDs, which may potentially reduce IQE of the nanorods LEDs. The anisotropic wet etch also allows precise control of the diameter and aspect ratio of the nanorod LEDs (FIG. 1.). The morphology of the nanorod LEDs was characterized by scanning electron microscopy and transmission electron microscopy. The optical performance of nanorod LEDs and planar LEDs was compared using photoluminescence (PL) studies. We observed that as the diameter of the nanorod LEDs decrease below 200 nm, the PL intensity increases dramatically and shows a total enhancement factor of 15 as compared with the planar LED samples. The IQE extracted from the temperature dependent PL studies revealed that IQE of the nanorod LEDs remains constant as compared with planar LEDs. Therefore, this top-down technique may be feasible for creating LEDs with high light extraction efficiency. In addition, the dislocation morphology in the nanorods LEDs were studied by TEM. We observed that the percentage of dislocation-free nanorod increases as their diameter decreases. This results suggest that the life time and and reliability of the nanorod LEDs may be improved due to the fact of majority of the nanorods are free of dislocations. Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under Contract No. DE-AC04-94AL85000. |
| Proceedings Inclusion? |
Undecided |