Structural changes during annealing of GaInAsN

The alloy GaInAsN has great potential as a lower-band-gap material lattice matched to GaAs, but there is little understanding of what causes its poor optoelectronic properties and why these improve with annealing. This study provides information about the structural changes that occur when GaInAsN i s annealed. The Fourier transform infrared spectra exhibit two primary feat ures: a triplet at similar to 470 cm(-1) (Ga-N stretch) and two or three ba nds at similar to 3100 cm(-1) (N-H stretch). The change in the Ga-N stretch absorption can be explained if the nitrogen environment is converted from NGa4 to NInGa3 after annealing. The N-H stretch is also changed after annea ling, implying a second, and unrelated, structural change. (C) 2001 America n Institute of Physics.