Structure optimisation of short-wavelength ridge-waveguide InGaN/GaN diode lasers

Room-temperature (RT) continuous-wave (CW) operation of the 405-nm ridge-waveguide (RW) InGaN/GAN quantum-well diode lasers equipped with the n-type GaN substrate and two contacts on both sides of the structure has been investigated with the aid of the comprehensive self-consistent simulation model. As expected, the mounting configuration (p-side up or down) has been found to have a crucial impact on the diode laser performance. For the RT CW threshold operation of the otherwise identical diode laser the p-side up RW laser exhibits as high as nearly 68 degrees C maximal active-region temperature increase whereas an analogous increase for the p-side down laser was equal to only 24 degrees C. Our simulation reveals that the lowest room-temperature lasing threshold may be expected for relatively narrow and deep ridges. For the structure under consideration, the lowest threshold current density of 5.75 kA/cm(2) has been determined for the 2.2-mu m ridge width and the 400-nm etching depth. Then, the active-region temperature increase was as low as only 24 K over RT For wider 5-mu m ridge, this increase is twice higher An impact of etching depth is more essential for narrower ridges. Quite high values (between 120 and 140 K) of the characteristic parameter To convince very good thermal properties of the above laser.