GaAs-substrate-based long-wave active materials with type-II band alignments

Abstract

The optimized growth conditions and evidence for type-II alignment in GaAsSb/InGaAs heterostructures are reported. The asymmetric GaAsSb/InGaAs bilayer quantum well grown on GaAs shows promising results for device applications around the wavelength of 1.3 m. Uncompensated type-II GaAs/GaAsSb/GaAs quantum-well systems and strain-compensated GaAsP/GaAs/GaAsSb/GaAs/GaAsP quantum-well systems are compared for 1.3 m applications. Inhomogeneous photoluminescence-linewidth broadening due to lateral composition and thickness variation is reduced from 74 to 40 meV when GaAsP strain-compensation layers are added to GaAsSb-based trilayer quantum-well systems.

Structural and optical properties of strain-compensated GaAsSb/GaAs quantum wells with high Sb composition

“…2,3 However, in straincompensated structure B344, the wave functions for electrons in the coupled double QW and holes in the deep step QW have a larger spatial overlap in the GaAsSb layer region. 7 Therefore, the half width of the PL peaks at both RT and low temperature is narrower for B344 than for B325 under the same excitation conditions as mentioned earlier, and the blueshift of PL peak induced by the increasing excitation intensity is much less than B325, demonstrating the fact that in the strain-compensated QW structure the optical transitions display a behavior similar to type-I QWs.…”

“…A reduced inhomogeneous broadening of the PL linewidth, due to lateral composition and thickness modulation, may be ascribed to the decrease in the strain accumulation and higher structure quality of strain-compensated QWs. 7 That is, the contribution of strain compensation to the overall structure is that it does not allow a significant amount of overall strain to accumulate as the layer is grown. Meanwhile, improvement in the PL emission strength is observed for the insertion of GaAsP layer.…”

“…Moreover, a poor electron confinement due to a type-II interface and a small band offset becomes an obvious drawback and will result in a low characteristic T 0 temperature. 7 In order to compensate for the compressive strain in GaAsSb/GaAs QWs and improve the confinement effects of electrons, additional tensile GaAsP barrier layers had been proposed to incorporate in the active region to form a strain-compensated coupled QW structure. [7][8][9] However, the detailed structural and optical properties as introducing the GaAsP tensile-compensation layers are still not reported.…”

“…7 In order to compensate for the compressive strain in GaAsSb/GaAs QWs and improve the confinement effects of electrons, additional tensile GaAsP barrier layers had been proposed to incorporate in the active region to form a strain-compensated coupled QW structure. [7][8][9] However, the detailed structural and optical properties as introducing the GaAsP tensile-compensation layers are still not reported. In this letter, we performed highresolution x-ray diffraction ͑HRXRD͒ and low-temperature photoluminescence ͑PL͒ measurements for both straincompensated and uncompensated GaAsSb/GaAs QWs structure, indicating that the insertion of strain-compensated GaAsP layers effectively improves the structural quality at a very high Sb composition in GaAs 1Ϫx Sb x layer up to 0.39.…”

High performance GaAsSb∕GaAs quantum well lasers

“…[13][14][15] GaAsSb QWs are highly strained ͑ϳ2.7% ͒ at the composition necessary to achieve 1.3 m emission. The strain not only limits the maximum QW number that can be grown without misfit dislocations but also results in the strain-driven in-plane composition fluctuations that cause inhomogeneous linewidth broadening 14 and reduce internal quantum efficiency.…”