IMPROVEMENT IN LASING CHARACTERISTICS OF II-VI BLUE-GREEN LASERS USING QUATERNARY AND TERNARY ALLOYS TO PRODUCED PSEUDOMORPHIC HETEROSTRUCTURES

Pseudomorphic heterostructures with increased electrical and optical confinement were used to improve II-VI blue-green laser operating characteristics. These lasers employ Zn1-xMgxSySe1-y alloys for the cladding layers, ZnSySe1-y for the waveguiding layers and Zn1-zCdzSe quantum wells for the active layer. The defect density through the active layer in such a heterostructure was found to range from less-than-or-equal-to 4 X 10(6) to 6 x 10(8) cm-2 . The density found in the active layer is directly related to the growth of the quaternary alloy which is often accompanied by a high density of stacking faults and threading dislocations. By comparing lasers with varying defect densities a direct correlation between the threshold current density and the structural quality has been observed. The lasers with the lowest defect density have threshold current densities of 400 A/cm2 (without facet coating) which are the lowest reported for II-VI devices and comparable to state-of-the-art III-V devices.