Conservation of quantum efficiency in quantum well intermixing by stress engineering with dielectric bilayers

Abstract

In semiconductor lasers, quantum well intermixing (QWI) with high selectivity using dielectrics often results in lower quantum efficiency. In this paper, we report on an investigation regarding the effect of thermally induced dielectric stress on the quantum efficiency of quantum well structures in impurity-free vacancy disordering (IFVD) process using photoluminescence and device characterization in conjunction with microscopy. SiO 2 and Si x O 2 /SrF 2 (versus SrF 2) films were employed for the enhancement and suppression of QWI, respectively. Large intermixing selectivity of 75 nm (125 meV), consistent with the theoretical modeling results, with negligible effect on the suppression region characteristics, was obtained. Si x O 2 layer compensates for the large thermal expansion coefficient mismatch of SrF 2 with the semiconductor and mitigates the detrimental effects of SrF 2 without sacrificing its QWI benefits. The bilayer dielectric approach dramatically improved the dielectric-semiconductor interface quality. Fabricated high power semiconductor lasers demonstrated high quantum efficiency in the lasing region using the bilayer dielectric film during the intermixing process. Our results reveal that stress engineering in IFVD is essential and the thermal stress can be controlled by engineering the dielectric strain opening new perspectives for QWI of photonic devices.

Large intermixing in the InGaP/InAlGaP laser structure using stress engineering at elevated temperature

“…QWI by Si 3 N 4 and suppression by SiO 2 in the single layer and bilayer of dielectrics at 800 o C offers high quantum efficiency, improved surface quality (except few defects), and good quantum well-intermixing selectivity in the InGaP/InAlGaP. These results are contrary to what is reported earlier in the case of multi-layer InGaAs/GaAs quantum well laser structure [14][15] . Previously we achieved the largest degree of QWI (~250 meV) for an annealing duration of 240s at 950°C, but the decreases in PL intensity and broadening of FWHM suggests degradation of the epitaxial quality.…”

Facet Cooling in High-Power InGaAs/AlGaAs Lasers

“…strate, 3000 nm n-AlGaAs cladding, 500 nm n-AlGaAs waveguide, 8 nm InGaAs QW, 500 nm p-AlGaAs waveguide, 1000 nm p-AlGaAs cladding and finally 100 nm GaAs cap layer [19]. In this study, 100 μm wide broad area high power laser diodes with different lasing cavity and window lengths were used to compare the performance of the lasers and their facet temperatures.…”

Reduced facet temperature in semiconductor lasers using electrically pumped windows

“…By extending the cold laser output window, the heat generated in the laser section can be separated from the output facet. The epitaxial structure of our GaAs-based laser emitting at 915 nm is composed of 3000 nm n-AlGaAs cladding, 500 nm n-AlGaAs waveguide, single InGaAs quantum well layer, 500 nm p-AlGaAs waveguide, 1000 nm p-AlGaAs cladding and 100 nm GaAs contact layer [12]. In this work, 5 mm long and 100 μm wide broad area high power laser diodes with standard single-section and proposed two-section lasers were used to compare their performance and facet temperatures.…”