Browsing by Author "Kyaw, Z. B."

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    Improved hole distribution in InGaN/GaN light-emitting diodes with graded thickness quantum barriers
    (AIP Publishing, 2013) Ju, Z. G.; Liu, W.; Zhang, Z. H.; Tan, S. T.; Ji, Y.; Kyaw, Z. B.; Zhang, X. L.; Lu, S. P.; Zhang, Y. P.; Zhu, B.; Hasanov, N.; Sun, X. W.; Demir, Hilmi Volkan
    InGaN/GaN light-emitting diodes (LEDs) with graded-thickness quantum barriers (GTQB) are designed and grown by metal-organic chemical-vapor deposition. The proposed GTQB structure, in which the barrier thickness decreases from the n-GaN to p-GaN side, was found to lead to an improved uniformity in the hole distribution and thus, radiative recombination rates across the active region. Consequently, the efficiency droop was reduced to 28.4% at a current density of 70 A/cm2, which is much smaller than that of the conventional equal-thickness quantum barriers (ETQB) LED, which is 48.3%. Moreover, the light output power was enhanced from 770 mW for the ETQB LEDs to 870 mW for the GTQB LEDs at 70 A/cm2. © 2013 AIP Publishing LLC.
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    On the origin of the redshift in the emission wavelength of InGaN/GaN blue light emitting diodes grown with a higher temperature interlayer
    (AIP Publishing, 2012-03-20) Ju, Z. G.; Tan S.T.; Zhang Z.-H.; Ji Y.; Kyaw, Z. B.; Dikme, Y.; Sun, X. W.; Demir, Hilmi Volkan
    A redshift of the peak emission wavelength was observed in the blue light emitting diodes of InGaN/GaN grown with a higher temperature interlayer that was sandwiched between the low-temperature buffer layer and high-temperature unintentionally doped GaN layer. The effect of interlayer growth temperature on the emission wavelength was probed and studied by optical, structural, and electrical properties. Numerical studies on the effect of indium composition and quantum confinement Stark effect were also carried out to verify the experimental data. The results suggest that the redshift of the peak emission wavelength is originated from the enhanced indium incorporation, which results from the reduced strain during the growth of quantum wells.