Local indium segregation and band structure in high efficiencygreen light emitting InGaN/GaN diodes
GaN/InGaN light emitting diodes (LEDs) are commercialized for lighting applications because of the cost efficient way that they produce light of high brightness. Nevertheless, there is significant room for improving their external emission efficiency from typical values below 10 percent to more than 50 percent, which are obtainable by use of other materials systems that, however, do not cover the visible spectrum. In particular, green-light emitting diodes fall short in this respect, which is troublesome since the human eye is most sensitive in this spectral range. In this letter advanced electron microscopy is used to characterize indium segregation in InGaN quantum wells of high-brightness, green LEDs (with external quantum efficiency as high as 15 percent at 75 A/cm2). Our investigations reveal the presence of 1-3 nm wide indium rich clusters in these devices with indium concentrations as large as 0.30-0.40 that narrow the band gap locally to energies as small as 2.65 eV.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director. Office of Science. Office of Computationaland Technology Research, UC Davis Contract DE-FG02-03ER46057; Alexander-von-Humboldt Foundation
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 891812
- Report Number(s):
- LBNL-56655; SSCOA4; R&D Project: 518804; BnR: KJ0200000; TRN: US200622%%358
- Journal Information:
- Solid State Communications, Vol. 137, Issue 4; Related Information: Journal Publication Date: 2006; ISSN 0038-1098
- Country of Publication:
- United States
- Language:
- English
Similar Records
The impact of trench defects in InGaN/GaN light emitting diodes and implications for the “green gap” problem
Alternating InGaN barriers with GaN barriers for enhancing optical performance in InGaN light-emitting diodes