Strain Compensated Algan/gan-bragg-reflectors With High Al Content Grown By Movpe

摘要

Fully strained Al_xGa_(1-x)N/GaN-Bragg-reflectors (DBR) with x > 0.4 have been grown on (0001) sapphire by metalorganic vapour phase epitaxy. We report on the fabrication of strain compensated DBR structures with a stop band in the blue green spectral region by using an underlying Al_(0.21)Ga_(0.79)N buffer layer. For a reactor pressure of 50 Torr and a N/Ⅲ ratio of less than 800 we were able to find a growth regime where parasitic prereactions of the precursors were neglected. Although a change in atmospheric composition from H_2 to N_2 has a significant influence on the growth rates of GaN and AlGaN, we see no impact on the optical properties of the grown structures.