The MOCVD Growth Research On AlGaN Epitaxial Layer With High-Al Concentration

The research of this paper is mainly based on MOCVD crystal growth technical, good-crystal-quality and crack free AlxGa1-xN epilayer with high-Al concentration have been grown on sapphire substrate through a series of growing and testing experiments. And the key point of the buffer layers, the influence factor of several process parameters to the crystal quality have been investigated from the both sides of crystal growth and characterization analysis.Then the process parameters are optimized step by step and the role of each parameter are forecasted during the growing process. Finally, through comparison of the experiment results, the optimized process parameters has been obtained and with which high-Al composition AlxGa1-xN material with best quality could be grown sucessfully.Based on the optimized process formula, AlxGa1-xN epilayers with different Al concentration have been grown by adjusting the incorporation of Al. And the real value of Al concentration are determined by XRD.Furthermore, the differences between density of both screw dislocation and edge dislocation have been investigated, and the paractical crystal constant are also be calculated.