Characterization of InGaN/AlGaN multiple-quantum-well laser diodes

This paper discusses the design and characteristics of III-nitride based multi-quantum well (MQW) laser diodes grown on a- as well as c-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). Threshold current densities as low as 4.8 kA/cm 2 have been observed on devices with CAIBE etched mirrors and a SiO 2 /TiO 2 high reflective coating on both facets. The lowest threshold currents obtained were around 55 mA (U th = 9.5V) for 3μm * 300μm ridge-waveguide laser diodes devices which allow room temperature pulsed operation up to 70% duty cycle (devices mounted p-side up). From cavity length studies the distributed loss in our structures was determined to be of the order of 35-45 cm -1 . At threshold this corresponds to a maximum modal gain of about 110 cm -1 or a material gain of about 2200 cm -1 .