Hybrid nitride microcavity using crack‐free highly reflective AlN/GaN and Ta 2 O 5 /SiO 2 distributed Bragg mirrors

We report the growth over 2 inch sapphire substrates of hybrid nitride‐based microcavities using one crack‐free highly reflective AlN/GaN distributed Bragg reflectors (DBRs) incorporated with AlN/GaN superlattice (SL) insertion layers and Ta 2 O 5 /SiO 2 DBRs. The optical cavity is formed by a 5 λ cavity consisting of n‐type GaN, 10 pairs multiple quantum wells and p‐type GaN sandwiched by AlN/GaN and Ta 2 O 5 /SiO 2 DBRs. Reflectivity and photoluminescence measurements were carried out on these structures. A 29 periods AlN/GaN DBR incorporated with six AlN/GaN superlattice insertion layers showed no observable cracks and achieved a peak reflectivity of 99.4% and a stopband of 21 nm. Based on these high quality DBRs, the cavity mode is clearly resolved with a linewidth of 2.6 nm. These results demonstrate that the AlN/GaN system is very promising for the achievement of strong light–matter interaction and the fabrication of nitride‐based vertical cavity surface emitting lasers. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)