Correlation of band formation and local vibrational mode structure in Ga(0.95)Al(0.05)As(1-x)N(x) with 0<= x <= 0.03

We present comprehensive optical studies of a series of as-grown and hydrogenated Ga(0.95)Al(0.05)As(1-x)N(x) epitaxial layers with various amounts x of substitutional nitrogen. Photomodulated and contactless electromodulated spectroscopies were performed to gain information about the influence of N incorporation on the band structure. The results are interpreted in terms of the band-anticrossing model and compared to corresponding GaAs:N data. The local vibrational properties of the N atoms studied by Raman and Fourier-transform infrared absorption were found to depend strongly on the Ga/Al nearest-neighbour configurations of N. Correlations between local N environments and global band structure properties are confirmed by comparing results obtained before and after hydrogenation of the samples.