Optical characterization of metalorganic vapor-phase epitaxy-grown GaAs1-xNx alloys using spectroscopic ellipsometry

We have measured complex dielectric functions, epsilon (1) + i epsilon (2), of GaAs1-xNx alloys using spectroscopic ellipsometry to investigate higher -energy band gaps. The E-1 gap-related peak height for epsilon (2) decrease s with increasing N concentration, indicating that the optical absorption a t the E-1 gap decreases. On the contrary, the E-2 gap transition does not c hange so much with varying N concentration. These results are consistent wi th the theoretical study, which predicts that the lowest conduction band is mostly a combination of the Gamma and L states. The bowing parameters of t he E-1 and E-2 yaps are rather large but much smaller than the bowing param eter of the E-o gap. (C) 2000 Elsevier Science B.V. All rights reserved.