Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

1 Publication
Optical and transport nonlinearities in quantum well infrared photodetectors
Schneider, H.; Maier, T.; Schönbein, C.; Koidl, P.; Walther, M.; Liu, H. C.;
Nonlinear behavior in quantum well infrared photodetectors (QWIPs) can be classified into nonlinearities associated with transport effects, such as quantum well depletion or photocurrent saturation induced by the emitter barrier, and nonlinearities induced by nonlinear absorption.
After giving a short overview on the different nonlinearities occurring in QWIPs and related device structures, we will concentrate on two particular phenomena. First, it is well known that the photoconductivity in n-type GaAs/AlGaAs QWIPs exhibits negative differential behavior, and that this negative differential photoconductivity gives rise to electric field domains. We have analyzed the spatial distribution of electric field domains induced by negative differential photoconductivity in a 50-period QWIP. We found evidence of two different domain configurations, with the high-field domain and the low-field domain, respectively, adjacent to the emitter contact. Second, we report on two-photon detection based on nonlinear absorption between subbands in quantum wells. Resonantly enhanced nonlinear absorption, six orders of magnitude higher as compared to typical bulk semiconductors, leads to a threshold power density for quadratic detection as low as 0.1 W/cm2, and femtosecond time resolution. The approach enables dynamical characterization of the optical light field of infrared emitters via autocorrelation measurements. We also demonstrate the use of this technique to investigate inter- and intra-subband scattering times.
Keywords: infrared, photodetector, intersubband, QWIP
  • Invited lecture (Conferences)
    8-th International Conference on Intersubband Transitions in Quantum Wells, 11.-16.09.2005, Cape Cod, MA, USA

Publ.-Id: 8046 - Permalink