Phosphorfree Whitelight Lightemitting Diodes Based on Prestrained InGaNGaN Quantum Wells

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Phosphor-free White-light Light-emitting Diodes
Based on Prestrained InGaN/GaN Quantum Wells
Chih-Feng Lu, Chi-Feng Huang, Dong-Ming Yeh,
Yung-Sheng Chen, Wen-Yu Shiao, and C. C.
Yang Institute of Photonics and Optoelectronics,
National Taiwan University
P-GaN
The violet QW creates a tensile strain in the
barrier layer right above it that helps in
lattice matching for the growth of the next QW.
The indium incorporation in the next QW can be
enhanced, leading to longer wavelength emission.
As we grew more high-indium QWs, the pre-strained
effect diminished.
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Photoluminescence(PL), cathodoluminescence(CL)
and Electroluminescence(EL) Spectra
Deeper QWs emit longer wavelengths
PL Spectra
CL of Control sample - A
CL of Prestrained sample - B
EL of Control sample - A
EL of Control sample - B
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Prestrained White-light Light-emitting Diode
Prestrained QW (7 indium)

• 1. The blue shifts of the EL spectra peaks are
  only 2.2 nm (blue), 11.6 nm (yellow) with
  injection current from 10 to 60 mA.
• 2. CIE chromaticity coordinates at 50 mA are
• (0.334, 0.338).
• 3. Color temperature is 5600 K.
• 4. 20mA voltage is about 4.3 V.