@InProceedings{Supelec670,
author = {Tarik Moudakir and Mohamed Abid and Bich-Thuy Doan and Etienne Demarly and Simon Gautier and Gaëlle Orsal and Joel Jacquet and Abdallah Ougazzaden and Frédéric Genty},
title = {{Asymmetrical design for non-relaxed near-UV AlGaN/GaN distributed Bragg reflectors}},
year = {2010},
booktitle = {{Proceedings of SPIE Photonics Asia}},
volume = {7847},
number = {78470B},
month = {18 - 20 October 2010},
address = {China National Convention Center Beijing, China},
url = {http://spie.org/x648.html\'eproduct_id=871826},
doi = {DOI: 10.1117/12.871826},
abstract = {Towards the development of high efficient GaN-based Vertical
Cavity devices, the fabrication of cracks-free high reflective
semiconductor mirrors is still an issue. For near-UV operating
devices, one of the best solution is the use of AlGaN/GaN
materials family. With a relatively high Al molar fraction in
AlGaN, a large enough index contrast can be achieved to fabricate
high reflectivity mirrors. However, the lattice mismatch between
AlGaN and GaN increases with the Al molar fraction and induces a
lot of cracks in the structure which affect its optical and
electrical properties. Moreover, for a regrowth of an active
layer on the top of the mirror, it is necessary to suppress crack
generations to achieve a smooth surface. In this work,
asymmetrical designs were investigated for the modeling of
fully-strained AlGaN/GaN distributed Bragg Reflectors with
crack-free surfaces. First, the critical thickness of MOVPE-grown
AlGaN on GaN-on-sapphire templates was experimentally determined
and modeled. Then, several AlGaN/GaN mirrors with various Al
molar fractions and asymmetry factors were simulated
demonstrating that non relaxed DBRs could be obtained with
adequate parameters. Finally, it has also been shown that there
is a best suited Al molar fraction in AlGaN for each DBR
centering wavelength.}
}