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Publication Date
May 26, 2017
Knowledge Repository of SEMI,CAS
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<div>The infrared laser has a significant value in gas detection, laser medication, spatial optical communication and military infrared counteration. The GaSb-based type I quantum well semiconductor laser has a prominent position in the 2 ~ 4μm band infrared laser because of its advantage in small size, high power, high efficiency and good environment adaptability. In-depth study and fabrication of GaSb-based quantum well lasers can not only meet the needs of the field in the infrared band laser, but also has strategic significance. In this paper, the molecular beam epitaxial growth conditions, structural design and fabrication process of high performance GaSb I type quantum well lasers are studied systematically. The preparation process and process characteristics of 2μm high order DBR lasers are studied by using the general technology platform.</div><div>(1) The lattice constants of InGaAsSb and AlGaAsSb were calculated by linear interpolation method Vegard's law in GaSb material system. The As composition of different group III components was obtained, and the lattice constants of AlGaInAsSb. The refractive index of InGaAsSb and AlGaAsSb under different wavelengths of 2 ~ 4μm was calculated by Sadao-Adachi approximation model. The optical limiting factor at 2 μm and 3 μm optical field is calculated according to the definition of the optical limiting factor with the former calculated refractive index parameter. The optical limiting factor varies with the thickness of the Al component and the thickness of the waveguide layer. Considering the series resistance and open voltage, the Al component range was limited from 0.5 to 0.7. The optimum waveguide layer thickness is corresponding to lasing wavelength;</div><div>(2) The growth parameters of InGaAsSb/AlGaAsSb in the epitaxial growth of MBE were studied. The optimum growth temperature of quantum wells operating at 2.6μm was 500 ℃, and the optimized quantum well strain was about 1.3%. The growth characteristics of AlGaInAsSb were studied. The lattice strain and surface morphology of AlGaInAsSb were characterized by HR-XRD, AFM and optical microscope. The lattice strain changes at different growth temperatures were obtained. The growth temperature of the AlGaInAsSb is similar to that of AlGaAsSb, and the growth window is above Tc + 45 ℃. The growth parameters of the quantum well InGaAsSb/AlGaInAsSb using the quinternary barrier are optimized. The growth of the quantum well above 2.7μm needs to be operated at a lower growth temperature, and 2.7 ~ 3.4μm room temperature PL spectra are obtained by introducing the interface controlling.</div><div>(3) According to the optimized growth conditions, 2 ~ 3 μm GaSb-based quantum well laser epitaxial structures were grown with MBE. 2.6μm diode lasers operating at room temperature with continuous wave were fabricated, and the maximum power was 325mW, the threshold current density was 402A / cm-2. 2.75μm diode lasers operating at room temperature with continuous wave were fabricated, and the maximum power was 60mW, the threshold current density was 533A / cm-2. Wavelength was expanded to 2.97μm with room temperature lasing, and the threshold current was 721A / cm-2.</div><div>(4) Based on the general processing conditions, a 2μm high-order DBR laser structure was designed. The fabrication of high-order DBR gratings was optimized for needs of the high-quality controllable high-order DBR grating by the optimization of ICP etching. The 2 μm high-order DBR laser device was fabricated by using the previously optimized etching scheme. The relationship between the quality of the mold selection and the depth of the grating groove and the duty ratio was studied. 2μm laser diodes operating at single wavelength mode in RT incontinuous wave were obtained, and the maximum side mode suppression ratio was up to 22.5dB.</div>

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