The band-gap bowing of AlxGa1-xN alloys

The band gap of AlxGa1-xN is measured for the composition range 0 less than or equal to x<0.45; the resulting bowing parameter, b=+0.69 eV, is compare d to 20 previous works. A correlation is found between the measured band ga ps and the methods used for epitaxial growth of the AlxGa1-xN:directly nucl eated or buffered growths of AlxGa1-xN initiated on sapphire at temperature s T>800 degrees C usually lead to stronger apparent bowing (b>+1.3 eV); whi le growths initiated using low-temperature buffers on sapphire, followed by high-temperature growth, lead to weaker bowing (b<+1.3 eV). Extant data su ggest that the intrinsic band-gap bowing parameter for AlGaN alloys is b=+0 .62(+/-0.45) eV. (C) 1999 American Institute of Physics. [S0003-6951(99)028 22-3].