Photocurrent spectroscopy of InxGa1-xAs/GaAs double quantum wells in a low electric field

We investigated the photocurrent (PC) of InGa1-xAs/GaAs double quantum wells grown by metalorganic chemical vapor deposition (MOCVD). From the PC spectra, we determined the intersubband transition energies. These values were in good agreement with the calculated values from the envelope function approximation. As the applied bias increased, the intensities corresponding to forbidden transitions became larger than allowed transitions due to an overlap between the electron and the hole wave functions. At the same time, the observed peaks were shifted to lower energies due to the quantum-confined Stark effect. In addition, we evaluated the applied electric field of resonant tunneling for excitonic transitions.