Milliampere-range 'twice-buried' AlGaAs-heterolasers fabricated by low-temperature liquid phase epitaxy

Abstract

The authors report on low-threshold quantum-well AlGaAs heterolasers emitting at wavelengths of 730-850 nm. A special LPE (liquid-phase epitaxy) technique has been developed to crystallize thin layer AlGaAs heterostructures in the low-temperature range of 400-600 degrees C. Values of threshold current density as low as 120 A/cm/sup 2/ at emitting wavelength lambda =845 nm and 380 A/cm/sup 2/ at lambda =760 nm were measured for wide-stripe geometry separate confinement lasers with 15-nm-thick active layers. 'Twice-buried' stripe laser heterostructures were developed to considerably narrow the width of the current channel, to confine the optical mode in lateral directions, and to compensate for the strain tensions in the active layer in order to solve the laser lifetime problem. Threshold currents as low as 2 mA at lambda =845 nm and 10 mA at lambda =765 nm were measured for 'twice-buried' stripe lasers without reflecting coatings on the facets (CW; T=300 K). The estimated lifetime was over 20000 h at room temperature.