MOCVD-Grown InGaAsP Double Heterostructure Diode Lasers

InGaAsP/InGaP/GaAs compound has been recently proposed to replace AlGaAs/GaAs as advantageous material for high-power laser applications. In this work we report successful fabrication and study of broad-area double- heterostructure InGaAsP/InGaP laser diodes reproducibly grown by MOCVD. The diodes demonstrated near-100% efficiency of spontaneous radiative recombination in the active region. Threshold current densities of 70OA/cm2 obtained for 900um-long cavities were close to the theoretically predicted low limit and lower than respective values experimentally obtained for similar AlGaAs/GaAs diodes. Narrow far-field distribution with FWHM of 28 deg in the direction transverse to p-n junction plane may be of practical interest. Saturation of spontaneous emission above the threshold as well as a flat near field pattern confirm the uniformity of lasing intensity across a 100um-wide stripe and the homogeneity of the structures studied. Relatively high internal losses of approximately 40cm-1 and low differential quantum efficiency of 25% were shown to be inherent for this laser structure design and should be overcome by a combination of the advantages of separate-confinement heterostructures with this laser-quality material.