Performance characteristics of buried heterostructure VCSELs using semi-insulating GaInP : Fe regrowth

We have fabricated GaAs-AlGaAs buried heterostructure vertical cavity surfa ce emitting lasers, emitting at 850 nm, using semi-insulating GaInP:Fe regr owth and investigated their static properties. Lasers of different size (10 -21 mum) have threshold currents in the range 2.8-7.0 mA, and produce a max imum output power of 1.7-6.0 mW at room temperature. The variation of thres hold current with device size shows that the leakage current at the regrowt h interface accounts for a significant part of the injection current. In sp ite of this, a differential quantum efficiency in the range 20%-30% is obta ined which indicates that the regrowth interface is smooth and does not int roduce any significant scattering loss. Studies of the transverse mode prop erties suggest that the GaInP provides weak guiding, resulting in single mo de operation up to an output power of 0.7 mW and a beam divergence of only 6 degrees for lasers as large as 10 mum.