Yao-Hong You

Suppressed quantum-confined Stark effect in InGaN-based LEDs with nano-sized patterned sapphire substrates.

This paper demonstrates that quantum-confined Stark effect (QCSE) within the multiple quantum wells (MQWs) can be suppressed by the growths of InGaN-based light-emitting diodes (LEDs) on the nano-sized patterned c-plane sapphire substrates (PCSSs) with reducing the space. The efficiency droop is also determined by QCSE. As verified by the experimentally measured data and the ray-tracing simulation results, the suppressed efficiency droop for the InGaN-based LED having the nano-sized PCSS with a smaller space of 200 nm can be acquired due to the weaker function of the QCSE within the MQWs as a result of the smaller polarization fields coming from the lower compressive strain in the corresponding epitaxial layers.

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

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).

Utilizing Two-Dimensional Photonic Crystals in Different Arrangement to Investigate the Correlation Between the Air Duty Cycle and the Light Extraction Enhancement of InGaN-Based Light-Emitting Diodes

This paper demonstrates that the optimal light extraction enhancement of the 2-D photonic crystals (PhCs) light-emitting diodes (LEDs) among different air duty cycles (ADADCsCs) is independent of the geometry and the shape of the 2-D PhCs. Moreover, it also discusses that the side-directional emission property of the 2-D PhCs LEDs in hexagonal lattice arrangement (HLA) is better than that in square lattice arrangement (SLA). Finally, the light output power of the 2-D PhCs LEDs in SLA and in HLA with the ADC of 51% are significantly improved by 60.4% and 81.9%, respectively, as compared with the reference LED at an injection current of 350 mA.

Enhanced performance of InGaN-based light-emitting diodes grown on volcano-shaped patterned sapphire substrates with embedded SiO2

This paper describes highly efficient InGaN-based light-emitting diodes (LEDs) grown on volcano-shaped patterned sapphire substrates with embedded SiO2 (SVPSS). Raman spectroscopy and transmission electron microscopy revealed that the LEDs grown on the SVPSS had high internal quantum efficiency resulting from relaxed compressive strain and fewer threading dislocations in the GaN epitaxial layers. Experimentally measured data and ray-tracing simulations suggested that the enhancement in the light extraction efficiency was due to the light scattering effect arising from the conical air voids and the gradual refractive index matching resulting from the embedded SiO2. Compared with a conventional LEDs operated at an injection current of 350 mA, the light output power from our LED grown on SVPSS was increased by 72%.

Performance enhancement in quantum well infrared photodetector utilizing the grating structure

We fabricate four different size grating structure on the top of the quantum well infrared photodetectors, then etch them into four different etching depth. With suitable design, the peak responsivity of the QWIPs is about thirteen times larger than that of the conventional QWIP.

Photovoltaic performance improvement of Si HIT solar cell by incorporating flower-like light trapping structures

We implemented the flower-like light trapping structures on the surface of HIT solar cell to achieve a great reflectance reduction and effectively improve the J_SC from 34.32 mA/cm² to 39.4 mA/cm² compared to the reference.

Reduced QCSE in InGaN-based LEDs by patterned sapphire substrates with enlarging the diameter of hexagonal hole

This paper reports the growths of InGaN-based light-emitting diodes (LEDs) on the patterned sapphire substrates (PSSs) with enlarging the diameter of hexagonal hole can reduce the related quantum-confined Stark effect (QCSE) within multiple-quantum wells (MQWs), resulting in that the PL relative intensity is enhanced by up to 95% as compared to the conventional one.

Utilizing Two-Dimensional Photonic Crystals to Investigate the Correlation between the Air Duty Cycle and the Light Extraction Efficiency of InGaN-Based Light-Emitting Diodes

By incorporating two-dimensional photonic crystals into the surface of InGaN-based LEDs, the strong correlation between the air duty cycle and the light extraction efficiency of LEDs was demonstrated by optical and electrical measurement results.

Utilizing two dimensional photonic crystals to study the relation between the air duty cycle and the light extraction efficiency of InGaN-based Light-Emitting Diodes

In this paper, we have fabricated two-dimensional (2-D) photonic crystals (PhCs) in order to obtain the high light extraction efficiency of InGaN-based Light Emitting Diodes (LEDs) and then we used front-side illuminated micro-photoluminescence (μ-PL) spectroscopy to measure the PL intensity of our InGaN-based LEDs, we also used back-side illuminated inverted microscopy to double check our PL intensity results. From the PL intensity results, not only a nearly threefold increase in the PL intensity was observed, but also that the light output intensity has the air duty cycle dependent characteristic was demonstrated.

The analysis of nano-patterned sapphire substrates-induced compressive strain to enhance quantum-confined stark effect of InGaN-based light-emitting diodes

This paper demonstrates that the quantum-confined stark effect of InGaN-based light-emitting diodes can be enhanced by the means of using the hexagonal nano-post patterned sapphire substrates based on the increase of the post-duty cycle.