Electronic bound states in the continuum above (Ga,In)(As,N)/(Al,Ga)As quantum wells

Using intersubband photocurrent spectroscopy, we have demonstrated that a bound state in the continuum exists above (Ga,In)(As,N)/(Al,Ga)As quantum wells. The photocurrent spectrum and responsivity show that the excited-state energies lie far above the potential barrier of the quantum well, and the bound nature of the states was confirmed from the long lifetime of the excited carriers and a small coupling with the surrounding continuum. Applying optical phonon scattering theory, we have demonstrated that the relaxation process is governed by scattering from localized nitrogen states to the three-dimensional continuum.