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Influence of patterned sapphire substrates with different symmetry on the light output power of InGaN-based LEDs.

You YH, Su VC, Ho TE, Lin BW, Lee ML, Das A, Hsu WC, Kuan CH, Lin RM - Nanoscale Res Lett (2014)

Bottom Line: The GaN epitaxial layers grown on the hexagonal lattice arrangement PSS (HLAPSS) have a lower compressive strain than the ones grown on the square lattice arrangement PSS (SLAPSS).The quantum-confined Stark effect (QCSE) is also affected by the residual compressive strain.Based on the experimentally measured data and the ray tracing simulation results, the InGaN-based LED with the HLAPSS has a higher LOP than the one with the SLAPSS due to the weaker QCSE within multiple-quantum wells (MQWs).

View Article: PubMed Central - HTML - PubMed

Affiliation: Graduate Institute of Electronic Engineering and Department of Electrical Engineering, National Taiwan University, No. 1, Roosevelt Road Section 4, Daan District, Taipei 10617, Taiwan.

ABSTRACT
This paper aims to investigate the light output power (LOP) of InGaN-based light-emitting diodes (LEDs) grown on patterned sapphire substrates (PSSs) with different symmetry. The GaN epitaxial layers grown on the hexagonal lattice arrangement PSS (HLAPSS) have a lower compressive strain than the ones grown on the square lattice arrangement PSS (SLAPSS). The quantum-confined Stark effect (QCSE) is also affected by the residual compressive strain. Based on the experimentally measured data and the ray tracing simulation results, the InGaN-based LED with the HLAPSS has a higher LOP than the one with the SLAPSS due to the weaker QCSE within multiple-quantum wells (MQWs).

No MeSH data available.


Related in: MedlinePlus

TracePro ray tracing results for the InGaN-based LEDs having the CSS, HLAPSS, and SLAPSS. The associated LEE with different samples is evaluated from the bare LED simulation results, and the insets show the cross-sectional ray tracing image.
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Figure 4: TracePro ray tracing results for the InGaN-based LEDs having the CSS, HLAPSS, and SLAPSS. The associated LEE with different samples is evaluated from the bare LED simulation results, and the insets show the cross-sectional ray tracing image.

Mentions: Based on the experimental results of Raman and excitation current-dependent EL measurement, it can be determined that the growths of the InGaN-based LED on the higher symmetry of HLAPSS can acquire a better crystalline quality. The superiority of this structure emerges from the relieved residual compressive strain of GaN epitaxial layers, which is accompanied by the reduction of polarization fields within the MQWs along with weaker QCSE. The abatement of QCSE within the MQWs can increase overlap between electron and hole wave functions and consequently result in a stronger radiative recombination rate.To obtain the LEE contribution of PSSs with different symmetry, a TracePro (Lambda Research Corporation, Littleton, MA, USA) ray tracing simulation was used to calculate the LEE of InGaN-based LEDs. FigureĀ 4 shows the correlated LEE of InGaN-based LEDs having the CSS and PSSs with different symmetry, and the inserted figures show the cross-sectional ray tracing image. The results reveal that the InGaN-based LEDs grown on SLAPSS and HLAPSS have the larger LEE than the one grown on the CSS due to the light scattering effect from PSSs. In addition, it is worth noting that the LEE of InGaN-based LEDs with the SLAPSS and HLAPSS are almost the same. This may be ascribed to the structural dimension, which is larger than the optical wavelength in the material. As a result, the higher symmetry of PSSs can only slightly influence the LEE.


Influence of patterned sapphire substrates with different symmetry on the light output power of InGaN-based LEDs.

You YH, Su VC, Ho TE, Lin BW, Lee ML, Das A, Hsu WC, Kuan CH, Lin RM - Nanoscale Res Lett (2014)

TracePro ray tracing results for the InGaN-based LEDs having the CSS, HLAPSS, and SLAPSS. The associated LEE with different samples is evaluated from the bare LED simulation results, and the insets show the cross-sectional ray tracing image.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4225452&req=5

Figure 4: TracePro ray tracing results for the InGaN-based LEDs having the CSS, HLAPSS, and SLAPSS. The associated LEE with different samples is evaluated from the bare LED simulation results, and the insets show the cross-sectional ray tracing image.
Mentions: Based on the experimental results of Raman and excitation current-dependent EL measurement, it can be determined that the growths of the InGaN-based LED on the higher symmetry of HLAPSS can acquire a better crystalline quality. The superiority of this structure emerges from the relieved residual compressive strain of GaN epitaxial layers, which is accompanied by the reduction of polarization fields within the MQWs along with weaker QCSE. The abatement of QCSE within the MQWs can increase overlap between electron and hole wave functions and consequently result in a stronger radiative recombination rate.To obtain the LEE contribution of PSSs with different symmetry, a TracePro (Lambda Research Corporation, Littleton, MA, USA) ray tracing simulation was used to calculate the LEE of InGaN-based LEDs. FigureĀ 4 shows the correlated LEE of InGaN-based LEDs having the CSS and PSSs with different symmetry, and the inserted figures show the cross-sectional ray tracing image. The results reveal that the InGaN-based LEDs grown on SLAPSS and HLAPSS have the larger LEE than the one grown on the CSS due to the light scattering effect from PSSs. In addition, it is worth noting that the LEE of InGaN-based LEDs with the SLAPSS and HLAPSS are almost the same. This may be ascribed to the structural dimension, which is larger than the optical wavelength in the material. As a result, the higher symmetry of PSSs can only slightly influence the LEE.

Bottom Line: The GaN epitaxial layers grown on the hexagonal lattice arrangement PSS (HLAPSS) have a lower compressive strain than the ones grown on the square lattice arrangement PSS (SLAPSS).The quantum-confined Stark effect (QCSE) is also affected by the residual compressive strain.Based on the experimentally measured data and the ray tracing simulation results, the InGaN-based LED with the HLAPSS has a higher LOP than the one with the SLAPSS due to the weaker QCSE within multiple-quantum wells (MQWs).

View Article: PubMed Central - HTML - PubMed

Affiliation: Graduate Institute of Electronic Engineering and Department of Electrical Engineering, National Taiwan University, No. 1, Roosevelt Road Section 4, Daan District, Taipei 10617, Taiwan.

ABSTRACT
This paper aims to investigate the light output power (LOP) of InGaN-based light-emitting diodes (LEDs) grown on patterned sapphire substrates (PSSs) with different symmetry. The GaN epitaxial layers grown on the hexagonal lattice arrangement PSS (HLAPSS) have a lower compressive strain than the ones grown on the square lattice arrangement PSS (SLAPSS). The quantum-confined Stark effect (QCSE) is also affected by the residual compressive strain. Based on the experimentally measured data and the ray tracing simulation results, the InGaN-based LED with the HLAPSS has a higher LOP than the one with the SLAPSS due to the weaker QCSE within multiple-quantum wells (MQWs).

No MeSH data available.


Related in: MedlinePlus