Conductive SiO2/HfO2 distributed Bragg reflector achieved by electrical breakdown and its application in GaN-based light emitters

Owing to the excellent optical reflectivity with wavelength tunability, dielectric distributed Bragg reflectors (DBRs) have attracted considerable interest in GaN-based light emitters. Yet, the non-conductive nature of the dielectric DBRs prevents current from passing through, leading to a current crowding effect and hampering dielectric DBRs from unlocking their full potential. In this paper, a conductive dielectric DBR was fabricated utilizing the electrical breakdown (EBD) technique. With the help of optical simulations, excellent optical properties were demonstrated by optimizing the structural designs with a high reflectivity of 98.3% at 450 nm based on 5.5 pairs SiO2/HfO2 DBRs. The outstanding electrical behaviors after the EBD process were verified by current-voltage curves and conductive atomic force microscopy characterization. Moreover, conductive mechanisms of this type of dielectric DBR were elaborated by comparing the EBD behaviors with different metal electrodes, suggesting that metal filaments play an important role in forming the conducting channels. Besides, 450 nm-emission with conductive 5.5 pairs SiO2/HfO2 DBR was successfully prepared, which proves that a conductive DBR can be successfully applied to GaN-based light-emitting devices. The conductive DBR presented in this work contributes to the acceleration of the development of high-power GaN-based solid-state light emitters.