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Doping density dependence of intersubband transitions in GaAs/AlxGa1-xAs quantum-well structures.

Dotierungsabhängigkeit der Intersubbandübergänge in GaAs/AlxGa1-xAs Quantentopfstrukturen

Journal of applied physics 67 (1990), Nr.8, S.3900-3903 : Abb.,Lit.
ISSN: 0021-8979
ISSN: 1089-7550
Fraunhofer IAF ()
infrared detector; Infrarotdetektor; intersubband transitionAB Intersubband transitions in GaAs/Al sub x Ga sub 1-xAs quantum wells have been studied as a function of the doping level by Raman scattering and infrared absorption. The n-type dopant concentration placed in the well was varied between 1 x 10 high 18 and 8 x 10 high 18 cm high -3. With increasing doping level Raman scattering reveals a frequency down-shift of the single-particle intersubband transition and a shift to higher frequencies of the collective intersubband plasmon-phonon mode. The resonance in infrared absorption follows closely the collective mode observed in Raman scattering, demonstrating clearly that the doping-dependent depolarization shift of the absorption peak is an important parameter that must be taken into account in device design. Possible models for the frequency down-shift of the single-particle transition are also discussed.