High power ultraviolet light emitting diodes based on GaN/AlGaN quantum wells produced by molecular beam epitaxy

Journal Article · Wed Nov 15 00:00:00 EST 2006 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2388127· OSTI ID:20884894

Cabalu, J S; Bhattacharyya, A; Thomidis, C; Friel, I; Moustakas, T D; Collins, C J; Komninou, Ph ^[1]

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1. Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215 and Center of Photonics Research, Boston University, Boston, Massachusetts 02215 (United States)

In this paper, we report on the growth by molecular beam epitaxy and fabrication of high power nitride-based ultraviolet light emitting diodes emitting in the spectral range between 340 and 350 nm. The devices were grown on (0001) sapphire substrates via plasma-assisted molecular beam epitaxy. The growth of the light emitting diode (LED) structures was preceded by detailed materials studies of the bottom n-AlGaN contact layer, as well as the GaN/AlGaN multiple quantum well (MQW) active region. Specifically, kinetic conditions were identified for the growth of the thick n-AlGaN films to be both smooth and to have fewer defects at the surface. Transmission-electron microscopy studies on identical GaN/AlGaN MQWs showed good quality and well-defined interfaces between wells and barriers. Large area mesa devices (800x800 {mu}m{sup 2}) were fabricated and were designed for backside light extraction. The LEDs were flip-chip bonded onto a Si submount for better heat sinking. For devices emitting at 340 nm, the measured differential on-series resistance is 3 {omega} with electroluminescence spectrum full width at half maximum of 18 nm. The output power under dc bias saturates at 0.5 mW, while under pulsed operation it saturates at approximately 700 mA to a value of 3 mW, suggesting that thermal heating limits the efficiency of these devices. The output power of the investigated devices was found to be equivalent with those produced by the metal-organic chemical vapor deposition and hydride vapor-phase epitaxy methods. The devices emitting at 350 nm were investigated under dc operation and the output power saturates at 4.5 mW under 200 mA drive current.

• OSTI ID: 20884894
• Journal Information: Journal of Applied Physics, Vol. 100, Issue 10; Other Information: DOI: 10.1063/1.2388127; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM NITRIDES
CHEMICAL VAPOR DEPOSITION
CRYSTAL GROWTH
ELECTRIC CONDUCTIVITY
ELECTROLUMINESCENCE
FABRICATION
GALLIUM NITRIDES
LAYERS
LIGHT EMITTING DIODES
MOLECULAR BEAM EPITAXY
QUANTUM WELLS
SAPPHIRE
SEMICONDUCTOR MATERIALS
SILICON
SUBSTRATES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
ULTRAVIOLET RADIATION
VAPOR PHASE EPITAXY