Quantum well design and diffraction efficiency of quantum well light emitting diode

Abstract

In this work, a GaN-based quantum well LED is theoretically analyzed in a multi-layer structure composed of a quantum well embedded in a waveguide core surrounded by photonic crystal slab and a sapphire substrate. The electromagnetic eigenmodes are obtained throughout above structure via revised plane wave-scattering matrix method. The omnidirectional transmission and reflection are investigated for both TE and TM polarizations from diffraction channels in Ewald construction. Then, we introduced angular power density and calculated radiative modes extraction efficiency. All structural parameters, such as lattice geometry, lattice constant, photonic crystal thickness and filling factor, are taken into account. We also investigated the coupling efficiency between waveguide modes and Bloch modes in structure which include decomposed emission and extraction regions. In order to design a quantum well white LED, we used a MQW with adjusted material composition. The photoluminescence spectrum for both TE and TM polarizations is obtained through a combination of k.p perturbation and transfer matrix method.

Performance Enhancement and Applications Review of Nano Light Emitting Device (LED)

“…As mentioned above, complementary investigation of how light is extracted from the nano-LED pixel is required. When the minimum feature size of a light source is of the same order as that of the wavelength of light, a rigorous electromagnetic analysis is needed for calculating the light extraction efficiency of photonic crystal LEDs [ 30 , 31 , 32 , 33 ]. Classical radiometry and common Monte-Carlo ray tracing cannot perform such investigation [ 34 , 35 ].…”

Light-emitting diode spherical packages: an equation for the light transmission efficiency

“…Eqs. (5) and (15) should be reduced to the LTE of a flat encapsulant if R, but the calculation of  becomes impractical because the coordinate system is moved to infinity.…”

“…In this section we apply Eqs. (5), (15), (18) and (19) for several different cases. The results are compared with those obtained through Monte-Carlo ray tracing with one million rays.…”

“…In this case light recycling becomes important. It can be shown that if one considers light recycling in LED chips, then the extracted light increases with respect to the case in which is disregarded [15,16]. Light recycling can also considerably increase the brightness of LEDs [34,35].…”

“…When the minimum feature size of a light source is of the same order as that of the wavelength of light, a rigorous electromagnetic analysis is needed, e.g. for calculating the light extraction efficiency of photonic crystal LEDs [14][15][16][17]. If the minimum size is much greater than the wavelength, the nonimaging optics approach is used [18,19].…”