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

Abstract

We report on low threshold current density (<400 A cm −2 ) injection lasing in (Al x Ga 1-x ) 0.5 In 0.5 P-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 metalorganic 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.

Room-temperature yellow-orange (In,Ga,Al)P–GaP laser diodes grown on (n11) GaAs substrates

“…InGaAlP regions were grown at ~750°C, and GaAs regions at ~700°C. 30 In 0.49 P lattice with a spatial resolution of 1 nm for ε zz and of 2 nm for ε xx by applying dark-field electron holography (DFEH) in high-resolution (HR) mode [19,26] at I2TEM-Toulouse, a HF3300 (Hitachi) TEM operating at 300 kV. The ε zz maps of the barriers indicate that the 4 nm-thick in-plane tensile strained layers contain about 40% of indium that was deduced by using elasticity theory and Vegard's law.…”

“…and [19], the vertical epitaxial design was aimed at achieving a reduced vertical beam divergence [32]. We apply tilted wave laser (TWL) concept [33] which is basically similar to the couple cavity design with a passive waveguide section matching the λ/2 condition.…”

“…However, no information was provided on the substrate orientation, the compositions and thicknesses of the cladding layers used for the optical and electron confinement, the cavity length and facet coating. Recently, it was reported that (In,Ga,Al)P light-emitting diodes grown on highindex GaAs substrates inclined from (100) towards <111>-crystallographic direction and containing tensile strained ultrathin GaP insertions showed an improved intensity of the electroluminescence at room temperature in the green spectral range of ~568 nm [19] as compared to (100)-grown devices [17,18]. The effect was attributed to the enhanced barrier heights in the conduction band for ultrathin tensile strained GaP barriers formed on surfaces close to the (111) GaAs orientation.…”

Non-invasive biomedical research and diagnostics enabled by innovative compact lasers

“…Within the past few decades, a variety of instrumental developments, primarily new lasers, detectors and methods have expanded the utility of spectroscopy for biomedical applications. Compact laser sources have proven their superior performance in stable line excitation over a range of wavelengths in the UV/visible (GaN based LED and laser diodes) [27], Red and Near IR (GaAs based lasers) [28,29], IR (InP, GaSb and QCL based lasers) [28,[30][31][32] regions.…”