| About this Abstract |
| Meeting |
2011 Electronic Materials Conference
|
| Symposium
|
2011 Electronic Materials Conference
|
| Presentation Title |
M8, Characterization of Green Semi-Polar (10-11) GaInN/GaN Light Emitting Diodes |
| Author(s) |
Christoph Stark, Shi You, Liang Zhao, Theeradetch Detchprohm, Christian Wetzel, Edward Preble, Tanya Paskova |
| On-Site Speaker (Planned) |
Christoph Stark |
| Abstract Scope |
The promise of for energy efficient, droop-free, color-stable, high brightness GaN light emitting diodes (LEDs) in the green-yellow spectral region has led to the exploration of epitaxial GaInN/GaN quantum well growth on the non-polar and semi-polar planes of GaN. Such structures avoid or at least reduce the large internal electric fields typical for polar c-plane-grown structures. These fields cause a strong variation of emission wavelength and most likely play a major role in the efficiency droop at high current densities. After achieving green LEDs on non-polar a- and m-planes we here explore the potential of semi-polar (10-11) plane for the same application. This plane frequently occurs as a highly stable facet in the growth of nanopillars. The residual electric fields are expected to promote longer emission wavelengths and to reduce optical re-absorption. GaInN/GaN multiple quantum well structures were grown in metal organic vapor phase epitaxy on the (10-11) prepared plane of hydride vapor phase c-axis grown bulk GaN. The LEDs structure includes an n-GaN layer, eight QWs, an AlGaN electron-blocking layer, and a p-GaN top contact layer. We reach a peak emission wavelength of up to 527 nm at 43 A/cm2, indicative of better Indium incorporation efficiency in the QWs, as compared to similar structures with nonpolar orientation. The film morphology is assessed by AFM, XRD, and TEM. Under variation of the drive current density over the device relevant range of 14 -- 94 A/cm2, the peak emission wavelength shows a minimal blue shift of less than 2 nm. The quantum efficiency and degree of optical polarization will be compared with competing structures. The wavelength stability around the desired operating current densities combined with the long emission wavelength makes this semi-polar crystallographic plane a highly promising candidate for the epitaxial growth of high power green LEDs as part of RGB solid state lighting solutions. This work was supported by a DOE/NETL Solid-State Lighting Contract of Directed Research under DE-EE0000627. This work was also supported by the National Science Foundation (NSF) Smart Lighting Engineering Research Center (# EEC-0812056). |
| Proceedings Inclusion? |
Undecided |