Influence of the a-directed off-cut on the opto-electrical properties of laser diodes grown on the 0.3° misoriented m-directed GaN substrate

We report on the results of the investigation of the influence of an additional a-directed off-cut of the substrate on the opto-electrical properties of the laser diodes grown on bulk GaN with initial misorientation 0.3° towards the m -direction. The investigated a -directed off-cut is varied from 0° up to 1° by means of multilevel laser lithography and dry etching. The results show that the increase of the a -directed off-cut causes the decrease of internal optical losses and increase of injection efficiency. In consequence, the devices fabricated on the wafer areas characterized by higher a-directed off cut are characterized by the lower threshold current, and higher slope and wall-plug efficiencies.