Band gap bowing parameter in pseudomorphic Al x Ga1− x N/GaN high electron mobility transistor structures

A method for evaluation of aluminium composition in pseudomorphic AlxGa1−xN layer from the measured photoluminescence (PL) peak energy is presented here. The layers were grown by metalorganic chemical vapor deposition and characterized by high resolution X-ray diffraction (HRXRD), PL, cathodoluminescence, and atomic force microscopy. We estimated the value of biaxial stress in pseudomorphic AlxGa1−xN layers grown on sapphire and silicon carbide substrates using HRXRD scans. The effect of biaxial stress on the room temperature band edge luminescence in pseudomorphic AlxGa1−xN/GaN layers for various aluminium compositions in the range of 0.2