We have investigated the effect of In/Ga ratio on InGaN waveguide layers obtained by the epitaxial growth, and analyzed their physical mechanisms in detail. It is found that enhancing the In/Ga ratio by increasing the TMIn flux and reducing the TEGa flux can alleviate the decrease of In composition in InGaN waveguide. Moreover, the intensity of the yellow band of the photoluminescence is obviously reduced due to the reduction of the residual carbon impurity concentration. The smaller scattering of injected carriers by impurities and defects is beneficial for enhancing the hole concentration in the p-type layer. Meanwhile, the results of Raman spectroscopy clarify that InGaN waveguide layers grown with larger In/Ga ratio can achieve higher carrier mobility and lower resistivity. Therefore, properly increasing the In/Ga ratio during the growth can effectively improve the crystal quality of InGaN waveguide layers, which facilitates the obtaining of high-performance GaN-based laser diodes. (c) 2021 Elsevier B.V. All rights reserved.
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