Almost temperature-insensitive characteristics in 1.06-um InGaAs laser diodes with strain-compensating electron-barrier layers

摘要

High-power single transverse-mode 1.06 $mu@m laser diodes are important for replacement of Nd:YAG lasers as fundamental light sources for green SHG lasers. Our Al-free InGaAs SQW laser diodes $LB@InGaAs/InGaAsP/InGa(As)P$RB grown by low-pressure MOVPE have shown that the increased In composition over 1.06 $mu@m deteriorates basic characteristics; that is, increased threshold current and shorter lifetime. The tensile-strained high-bandgap (In)GaAsP barrier layers are incorporated to compensate high compressive strain of an InGaAs quantum well to suppress the overflow of electrons from a quantum well. For 50-$mu@m wide broad area lasers, the threshold current is reduced and the lifetime is markedly improved by using strain compensating barrier layers. For single transverse mode operation, the buried ridge structure with a high bandgap AlGaInP current blocking layer is employed in order to avoid the excess current leakage. With using these schemes, almost temperature insensitive light-current curves have been obtained over 20 - 80$DGR@C. For a device as cleaved, the threshold current increases from 17.1 to 21.7 mA for the temperature range of 20 - 80$DGR@C. The slope efficiency of 0.4 W/A/facet is unchanged for the same temperature range up to 60 mW/facet. Characteristic temperature T$-0$/ for the threshold current is 437 and 175 K for the temperature range of 20 - 50 and 50 - 80$DGR@C, respectively.