Present status of short-wavelength group-III nitride-based laser diodes

摘要

Abstract: The continuous-wave (CW) operation of InGaN multi-quantum- well-structure laser diodes (LDs) was demonstrated at room temperature (RT) with a lifetime of 35 hours. The threshold current and the voltage of the LDs were 80 mA and 5.5 V, respectively. The threshold current density was 3.6 kA/cm$+2$/. Longitudinal modes with a mode separation of 0.042 nm were observed under CW operation at RT. When the temperature of the LDs was varied, large mode hopping of the emission wavelength was observed. The peak wavelength also showed mode hopping toward higher energy with increasing operating current. Each single-mode laser emission was located at a peak of each periodic subband emission. These periodic subband emissions probably result from the transitions between the subband energy levels of the InGaN quantum dots formed from In-rich regions in the InGaN well layers. The carrier lifetime and the threshold carrier density were estimated to be 10 ns and 2 $MUL 10$+20$//cm$+3$/, respectively. The beam full width at half- power values for the parallel and the perpendicular near- field patterns were 1.6 $mu@m and 0.8 $mu@m, respectively. Those of the far-field patterns were 6.8 degrees and 33.6 degrees, respectively. !18