REMARKABLE REDUCTION OF THRESHOLD CURRENT-DENSITY BY SUBSTRATE MISORIENTATION EFFECTS IN 660 NM VISIBLE-LIGHT LASERS WITH GAINP BULK ACTIVE LAYERS

660 nm wavelength GaInP/AlInP visible lasers with 60 nm thick GaInP active layers were grown on misoriented (100) GaAs substrates by gas source molecular beam epitaxy. A remarkable reduction in threshold current density J(th) was observed with increasing substrate misorientation angle (SMA) from the (100) surface toward the [011] direction. J(th) was 1.23 kA/cm2 on average for SMA of 0-degrees, and 841 A/cm2 for SMA of 15-degrees (both cavity lengths were 600-mu-m). For 1.1 mm long cavity lasers, a minimum J(th) was 702 A/cm2 which was obtained for ordinary bulk-crystal active layers without strain and quantum-well effects. Such misorientation effects on reduction of J(th) was systematically discussed in relation to various lasing parameters.