Green, yellow and bright red (In,Ga,Al)P-GaP diode lasers grown on high-index GaAs substrates

International audienceLow threshold current density (<400 A/cm2) injection lasing in (AlxGa1–x)0.5In0.5P–GaAs–based diodes down to the green spectral range (<570 nm) is obtained. The epitaxial structures are grown on high–index (611)A and (211)A GaAs substrates by metal–organic vapor phase epitaxy and contain tensile–strained GaP–enriched insertions aimed at preventing escape of the injected nonequilibrium electrons from the active region. Extended waveguide concept results in a vertical beam divergence with a full width at half maximum of 15o for (611)A substrates. The lasing at 569 nm is realized at 85 K. In the orange–red laser diode structure low threshold current density (200 A/cm2) in the orange spectral range (598 nm) is realized at 85 K. The latter devices demonstrate room temperature lasing at 628 nm at ~2 kA/cm2 and a total power above 3W. The red laser diodes grown on (211)A substrates demonstrate vertically multimode lasing far field pattern indicating a lower optical confinement factor for the fundamental mode as compared to the devices grown on (611)A. However the temperature stability of the threshold current and the wavelength stability are significantly higher for (211)A–grown structures in agreement with the conduction band modeling data

(In,Ga,Al)P-GaP laser diodes grown on high-index GaAs surfaces emitting in the green, yellow and bright red spectral range

International audienceWe report on low threshold current density (<400 A cm−2) injection lasing in (Al x Ga1–x )0.5In0.5P–GaAs-based diodes down to the green spectral range (<570 nm). The epitaxial structures are grown on high-index (611)A and (211)A GaAs substrates by metal–organic vapor phase epitaxy and contain tensile-strained GaP-enriched insertions aimed at reflection of the injected nonequilibrium electrons preventing their escape from the active region. Extended waveguide concept results in a vertical beam divergence with a full width at half maximum of 15° for (611)A substrates. The lasing at the wavelength of 569 nm is realized at 85 K. In an orange–red laser diode structure low threshold current density (190 A cm−2) in the orange spectral range (598 nm) is realized at 85 K. The latter devices demonstrated room temperature lasing at 628 nm at ~2 kA cm−2 and a total power above 3 W. The red laser diodes grown on (211)A substrates demonstrated a far field characteristic for vertically multimode lasing indicating a lower optical confinement factor for the fundamental mode as compared to the devices grown on (611)A. However, as expected from previous research, the temperature stability of the threshold current and the wavelength stability were significantly higher for (211)A-grown structures

Broad-area InAs/GaAs quantum dot lasers incorporating intermixed passive waveguide

InAs/GaAs quantum dot lasers incorporating passive waveguide created by post-growth intermixing processing have been studied. Emission wavelength of the passive section shows relative blueshift as high as 135 nm with respect to the emission wavelength of the active section. Intrinsic losses in the section formed by the intermixing are very small. Broad-area lasers with 100 µm stripe width incorporating intermixed section have demonstrated improvements in far-field pattern under both pulsed and continuous wave pumping current

Green (In,Ga,Al)P-GaP light-emitting diodes grown on high-index GaAs surfaces

International audienceWe report on green (550–560 nm) electroluminescence (EL) from (Al0.5Ga0.5)0.5In0.5P–(Al0.8Ga0.2)0.5In0.5P double p–i–n heterostructures with monolayer–scale tensile strained GaP insertions in the cladding layers and light–emitting diodes (LEDs) based thereupon. The structures are grown side–by–side on high–index and (100) GaAs substrates by molecular beam epitaxy. Cross–sectional transmission electron microscopy studies indicate that GaP insertions are flat, thus the GaP–barrier substrate orientation–dependent heights should match the predictions of the flat model. At moderate current densities (~500 A/cm2) the EL intensity of the structures is comparable for all substrate orientations. Opposite to the (100)–grown strictures, the EL spectra of (211) and (311)–grown devices are shifted towards shorter wavelengths (~550 nm at room temperature). At high current densities (>1 kA/cm2) a much higher EL intensity is achieved for the devices grown on high–index substrates. The integrated intensity of (311)–grown structures gradually saturates at current densities above 4 kA/cm2, whereas no saturation is revealed for (211)–grown structures up to the current densities above 14 kA/cm2. We attribute the effect to the surface orientation–dependent engineering of the GaP band structure which prevents the escape of the nonequilibrium electrons into the indirect conduction band minima of the p– doped (Al0.8Ga0.2)0.5In0.5P cladding layers