Resonance spectroscopy of InGaAs/InP quantum well sub-bands

The authors report on the infrared excitation of sub-band levels in doped InGaAs/InP quantum wells. Periodic multi-quantum-well structures and a single well have been studied. Strong resonance transitions are observed when both sub-band wavefunctions are confined to the quantum well. The experimental transition energies are compared with the results of a self-consistent potential calculation. By scanning the infrared excitation across the sample, inhomogeneities are studied with a spatial resolution of approximately=1 mm2.