Abstract
Replacing small amounts of As with Bi in InGaBiAs/InP induces large decreases and increases in the bandgap, E, and spin-orbit splitting, Δ, respectively. The possibility of achieving Δ > E and a reduced temperature (T) dependence for E are significant for suppressing recombination losses and improving performance in mid-infrared photonic devices. We measure E (x, T) and Δ (x, T) in InGa BiAs/InP samples for 0 x 0.039 by various complementary optical spectroscopic techniques. While we find no clear evidence of a decreased dE/dT (≈0.34 ± 0.06 meV/K in all samples) we find Δ > E for x > 3.3-4.3. The predictions of a valence band anti-crossing model agree well with the measurements. © 2012 American Institute of Physics.