Photon Management Employing Photonic Crystal in InGaN Quantum Well Based Devices
Date Issued
2012
Date
2012
Author(s)
Fu, Po-Han
Abstract
In this study, the schemes of enhancing the performances of indium gallium nitride (InGaN) based multiple quantum well (MQW) solar cells and light-emitting diodes (LEDs) are investigated. For the enhancement of conversion efficiencies of solar cells, SiO2 nano-honeycomb photonic crystals are fabricated on the devices. The nano-honeycombs are found to be effective in suppressing the undesired surface reflections over visible wavelengths. Under the illumination of air mass 1.5G solar simulator, conversion efficiency of the solar cell is enhanced by 34 %. To investigate light propagation behaviors across the interfaces, simulations based on finite-difference time-domain (FDTD) method are also carried out. In addition, 3 layer of PS nanospheres can be coated on the device based on the optimization design by simulations, contributing to the 30% enhancement of conversion efficiency.
One of the major bottlenecks restricts light extraction efficiency of LEDs is the limited photon escape cone for light emission. SiO2 nano-honeycombs diffract the waveguide mode out of the device by providing an additional wave vector. At the current injection of 400mA, the optical power of the device is enhanced by 78 %.
Subjects
photonic crystals
indium gallium nitride, quantum wells
solar cells
light-emitting diodes
Type
thesis
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