High quality UV AlGaN/AlGaN distributed Bragg reflectors and microcavities

摘要

We demonstrate high-reflectivity crack-free Al_(0.18)Ga_(0.82)N/Al_(0.8)Ga_(0.2)N distributed Bragg reflectors (DBR) and monolithic microcavities grown by molecular beam epitaxy on thick c-axis GaN templates. The elastic strain energy in the epilayer is minimized by compensating the compressive and tensile stress in every period of the DBR structure. A 25 period DBR mirror provides a 26nm-wide stop band centered at 347 nm with the maximum reflectivity higher than 99%. The high-reflectivity DBRs can be used to form high Q-factor monolithic AlGaN/AlGaN microcavities.