Low damage GaInAsP/InP nano-structures by CH4/H2 reactive ion etching and its application to low threshold gain-coupled DFB lasers

Low damage GaInAsP/InP narrow wire structures with good vertical mesa shape were realized by CH₄/H₂-reactive ion etching followed by a slight wet chemical etching and organo-metallic vapor phase epitaxy. The damage property of this fabrication process was characterized by the product of the sidewall recombination velocity and the carrier lifetime, which was measured from the wire width dependence of the photoluminescence intensity, to be 28 nm at room temperature. By using this fabrication process, 1.55 μm wavelength five-quantum-well distributed feedback (DFB) laser with a threshold current density as low as 330 A/cm² (66 A/cm²/well, @L=860 m) was obtained. To our knowledge this is the lowest value reported for 1.55 μm GaInAsP/InP DFB lasers fabricated by dry etching process