Contribution to the numerical modeling and simulation of multilayer heterojunction light-emitting diodes Contribution à la modélisation et à la simulation numériques des diodes électroluminescentes à hétérojonction multicouches

Abstract

Nitride-based semiconductor materials have wide energy band gap that can cover the spectrum between the deep ultraviolet and the infrared. Meaning that they can generate all the spectrum color in the visible region and they are almost universally used for making full color displays, white light (LED) and violet lasers. They emerged as the leading material in the optoelectronic technology. Their dominance have remained unchallenged until now. In this thesis, many structures of quantum wells light emitting diodes are designed, and simulated. They are a Green and violet SQW LEDs, dual color LEDs with two staked QWs using conventional structure, two vertically arranged SQW LED, and two laterally arranged SQW LED. Where, III-nitride materials are used. The structures have been numerically investigated using TCAD SILVACO-Atlas simulation software. The two last proposed structures have both three electrodes. This gives the opportunity to emit violet (410-420 nm) or green (561-562 nm) light individually. Furthermore, they can emit simultaneously mixture of both colors, and at certain mixture ratio, the white light is obtained with chromaticity coordinate close to the standard norm. In the structure, where a two (SQW) are vertically arranged, better mixture colors is obtained. In the structure, where (SQW) are laterally arranged, a reduction of the negative effect of photon absorption is obtained, which will give a good external quantum efficiency (EQE). The two last designed structures have a big importance in the application of the solid-state lighting, especially for white and multicolor light generation.