Analysis of Band Offset in GaNAs/GaAs by X-Ray Photoelectron Spectroscopy

We used X-ray photoelectron spectroscopy (XPS) to measure the energy discontinuity in the valence band (Δ E v) of Ga1-x N x As/AlAs (x=0, 0.014, 0.034) and estimated Δ E v of GaNAs/GaAs by using the Al2p energy level as a reference. The change in Δ E v for GaNAs/GaAs with an increasing nitrogen content was -(0.019±0.053) eV/%N. This suggests that the valence-band edge (E v) in GaNAs decreases in proportion to the nitrogen content. Based on the decrease in the bandgap energy of GaNAs, we found that the energy discontinuity in the conduction band (Δ E c) of GaNAs/GaAs is -(0.175±0.053) eV/%N. This large effect of bandgap bowing on the conduction band indicates that an ideal carrier confinement in the well can be obtained by using GaInNAs as an active layer in long-wavelength laser diodes.