Measurements of refractive index step and of carrier confinement at (AlGa)As–GaAs heterojunctions

The refractive index difference at the GaAs lasting wavelength of $\text{[inverted lazy s]\hspace{0.17em}9000\hspace{0.17em}Å}$ has been experimentally determined, from the measured beam profile, for a range of (AlGa)As–GaAs heterojunctions of practical interest. Good agreement is found with values calculated from the change in band gap with increasing Al in (AlGa)As. We have also shown by direct measurement that the loss of electron confinement at p⁺‐p heterojunctions follows a thermally activated process with activation energy equal to the difference in band gap at the heterojunction.