Stress-induced piezoelectric field in GaN-based 450-nm light-emitting diodes
- Department of Materials Science and Engineering, Chonnam National University, Yongbong 300 Gwangju 500-757 (Korea, Republic of)
We investigated the influence of the built-in piezoelectric field induced by compressive stress on the characteristics of GaN-based 450-nm light-emitting diodes (LEDs) prepared on sapphire substrates of different thicknesses. As the sapphire substrate thickness was reduced, the compressive stress in the GaN layer was released, resulting in wafer bowing. The wafer bowing-induced mechanical stress altered the piezoelectric field, which in turn reduced the quantum confined Stark effect in the InGaN/GaN active region of the LED. The flat-band voltage was estimated by measuring the applied bias voltage that induced a 180° phase shift in the electro-reflectance (ER) spectrum. The piezoelectric field estimated by the ER spectra changed by ∼110 kV/cm. The electroluminescence spectral peak wavelength was blue-shifted, and the internal quantum efficiency was improved by about 22% at a high injection current of 100 mA. The LED on the 60-μm-thick sapphire substrate exhibited the highest light output power of ∼59 mW at an injection current of 100 mA, with the operating voltage unchanged.
- OSTI ID:
- 22308193
- Journal Information:
- Journal of Applied Physics, Vol. 116, Issue 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CURRENTS
ELECTRIC POTENTIAL
ELECTROLUMINESCENCE
GALLIUM NITRIDES
INJECTION
LAYERS
LIGHT EMITTING DIODES
PHASE SHIFT
PIEZOELECTRICITY
QUANTUM EFFICIENCY
REFLECTION
SAPPHIRE
SPECTRA
STARK EFFECT
STRESSES
SUBSTRATES
THICKNESS
VISIBLE RADIATION
WAVELENGTHS