Optical investigation of delta-doped In0.1Ga0.9As-Si/GaAs strained quantum wells.
Optische Untersuchung Delta-dotierter In0.1Ga0.9As-Si/GaAs verspannter Quantum Wells
Photoluminescence and Raman spectroscopy have been used to study a Delta-doped Insub0.1Gasub0.9As:Si/GaAs strained quantum well with the doping spike placed at the centre of the 30 nm wide well. In this structure the potential confining the electron gas is given by a superposition of the V-shaped potential well induced by the doping spike and barriers introduced by the heterointerfaces. Both luminescence and intersubband Raman spectra provide information on the energy spacing and population of the electron subbands. A comparison with results of self-consistent subband calculations is made. Raman spectra exicited in resonance with the Esub0plusDeltasub0 bandgap of the Insub0.1Gasub0.9As quantum well show intense singleparticle intersubband transitions, which dominate over the signal from collective spin-density and charge-density excitations. Possible mechanisms for the occurrence of such strong single-particle intersubband Raman signals are discussed.