3 W cw output power has been obtained from aluminum-free, strained-layer double-quantum well ͑DQW͒ InGaAs/InGaAsP/InGaP uncoated, 100-m-wide stripe diode lasers ͑ϭ0.945 m͒ grown by low-pressure MOCVD on exact ͑100͒ GaAs substrates. The combination of high-band-gap ͑1.62 eV͒ InGaAsP confinement layers and the DQW structure provides relatively weak temperature dependence for both the threshold current I th as well as the external differential quantum efficiency d . Furthermore, the series electrical resistance for 100 mϫ600 m stripe-contact devices is as low as 0.12 ⍀. As a result, the power conversion efficiency reaches a maximum of 40% at 8 ϫI th , and decreases to only 33% at the maximum power ͑i.e., 3 W͒ at 28ϫI th . Low-temperature ͑12 K͒ photoluminescence measurements of InGaAs/InGaAsP quantum-well structures exhibit narrow linewidths ͑Ͻ10 meV͒ for material grown on exact ͑100͒ GaAs substrates, while growths on misoriented substrates exhibit linewidth broadening, as a result of ''step bunching.'' Laser structures grown on misoriented substrates exhibit increased temperature sensitivity of both I th and d , compared with structures grown on exact ͑100͒ substrates. © 1995 American Institute of Physics.Strained-layer quantum-well InGaAs lasers ͑980 nm͒ are needed as high-output-power pump sources for Er-doped fiber and waveguide amplifiers as well as for fluoride-fiberbased frequency upconversion. The use of the aluminum-free InGaAs/InGaAsP/InGaP material system has several advantages over the InGaAs/GaAs/AlGaAs material system for the realization of reliable, high-power diode sources: ͑1͒ the low reactivity of InGaP to oxygen facilitates regrowth for the fabrication of single-mode index-guided structures, 1,2 ͑2͒ higher electrical and thermal conductivity compared with AlGaAs, 3 and ͑3͒ lasers with AlGaAs cladding layers and unpassivated facets show higher facet degradation than similar lasers with InGaP cladding layers, 4 presumably due to the lower surface recombination velocity of InGaP 5 compared with AlGaAs. Al-free lasers also exhibit an order of magnitude lower facet temperature rise compared with devices containing AlGaAs in both the confining and cladding layers. 6 Although high performance has been demonstrated from Al-free laser structures, the characterization of the quantum-well growth for this material system and its influence on device performance have not been established.Achieving high cw output power requires weak temperature dependence of both the threshold current, I th , and differential quantum efficiency, d which in turn are influenced by carrier leakage from the quantum well͑s͒. Al-free lasers with GaAs or low-band-gap InGaAsP confinement layers exhibit strong carrier leakage from the InGaAs quantum well to the ͑optical͒ confinement layers, resulting in a strong temperature dependence of both I th and d . [7][8][9] To circumvent this problem, the use of higher band-gap InGaAsP confinement layers and multiple quantum wells have been used to reduce carrier leakage, and thereby reduce temp...

Dense arrays of indium arsenide (InAs) nanowire materials have been grown by selective-area metal-organic vapor-phase epitaxy (SA-MOVPE) using polystyrene-b-poly(methyl methacrylate) (PS/PMMA) diblock copolymer (DBC) nanopatterning technique, which is a catalyst-free approach. Nanoscale openings were defined in a thin (~10 nm) SiNx layer deposited on a (111)B-oriented GaAs substrate using the DBC process and CF4 reactive ion etching (RIE), which served as a hard mask for the nanowire growth. InAs nanowires with diameters down to ~ 20 nm and micrometer-scale lengths were achieved with a density of ~ 5 × 10(10) cm(2). The nanowire structures were characterized by scanning electron microscopy and transmission electron microscopy, which indicate twin defects in a primary zincblende crystal structure and the absence of threading dislocation within the imaged regions.

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