In this paper, a thermally induced dielectric strain on quantum well intermixing (QWI) technique is employed on tensilestrained InGaP/InAlGaP laser structure, to promote inter-diffusion, in conjunction with cycle annealing at elevated temperature. A bandgap blueshift as large as large as ~250meV was observed for samples capped with a single and bilayer of the dielectric film (1μm-SiO2 and 0.1μm-Si3N4) and annealed at a high temperature (700-1000oC) for cycles of annealing steps. Samples subjected to this novel QWI technique for short duration and multiple cycle annealing steps shown a high degree of intermixing while maintaining strong photoluminescence (PL) intensity, narrow full wave at half maximum (FWHM) and good surface morphology. Laser devices fabricated using this technique, lased at a wavelength of 608nm with two facet power of ~46mW, indicating the high quality of the material. Our results show that thermal stress can be controlled by the engineering dielectric strain opening new perspectives for QWI of photonics devices.
We achieved considerable laser diode (LD) improvement after annealing InGaP/InAlGaP laser structure at 950°C for a total annealing time of 2 min. The photoluminescence intensity is increased by 10 folds and full-wave at half-maximum is reduced from ∼30 to 20 nm. The measured LDs exhibited significantly reduced threshold current (Ith), from 2 to 1.5 A for a 1-mm long LD, improved internal efficiency (ηi), from 63% to 68%, and increased internal losses αi, from 14.3 to 18.6 cm−1. Our work suggests that the use of strain-induced quantum well intermixing is a viable solution for high-efficiency AlGaInP devices at shorter wavelengths. The advent of laser-based solid-state lighting (SSL) and visible-light communications (VLC) highlighted the importance of the current findings, which are aimed at improving color quality and photodetector received power in SSL and VLC, respectively, via annealed red LDs.
We increased the Al content in the single quantum well InGaP/InAlGaP laser by strain-induced quantum well intermixing, and obtained a considerable enhancement (close to ten-fold increase) in the photoluminescence (PL) intensity. Among the annealing process investigated, we achieved lasing at 638 nm in conjunction with reduction in the lasing threshold current by close to 500 mA in a moderately intermixed laser. Lasing in orange color, as well as spontaneous emission in the yellow and green color regime, were also achieved by extending the annealing conditions. The significance of the current work became apparent when one considers that achieving these tunable wavelengths by increasing the Al content in quantum wells during epitaxy growth leads to severe lattice-mismatch and poor material quality. Hence, our Al "drive-in" intermixing process is a viable approach for forming Al-rich InAlGaP quantum well, which is essential for realizing efficient optoelectronic devices in the "green-yellow-orange gap".
In this paper, a novel strain-induced quantum well intermixing (QWI) technique is employed on InGaP/InAlGaP material system to promote interdiffusion via application of a thick-dielectric encapsulant layer, in conjunction with cycle
annealing at elevated temperature. Broad area devices fabricated from this novel cost-effective QWI technique lased at
room-temperature at a wavelength as short as 608nm with a total output power of ~46mW. This is the shortest-
wavelength electrically pumped visible semiconductor laser, and the first report of lasing action yet reported from post-
growth interdiffused process. Furthermore, we also demonstrate the first yellow superluminescent diode (SLD) at a
wavelength of 583nm with a total two-facet output power of ~4.5mW - the highest optical power ever reported at this wavelength in this material system. The demonstration of the yellow SLD without complicated multiquantum barriers to
suppress the carrier overflow will have a great impact in realizing the yellow laser diode.
Simulating light propagation in anisotropic dynamic gain media such as semiconductors and solid-state lasers using the finite difference time-domain FDTD technique is a tedious process, as many variables need to be evaluated in the same instant of time. The algorithm has to take care of the laser dynamic gain, rate equations, anisotropy and dispersion. In this paper, to the best of our knowledge, we present the first algorithm that solves this problem. The algorithm is based on separating calculations into independent layers and hence solving each problem in a layer of calculations. The anisotropic gain medium is presented and tested using a one-dimensional set-up. The algorithm is then used for the analysis of a two-dimensional problem.
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