We study the influence on the photocurrent of the final state in bound-to-quasibound transitions in self-assembled quantum dot infrared photodetectors. We investigate two structures designed to explore different mechanisms of carrier extraction and therefore achieve a better insight on these processes. We observe photocurrent in opposite directions, with positive and negative sign, for different incident frequencies at the same applied external electric field. This phenomenon is attributed to the asymmetry of the potential barriers surrounding the quantum dots.

Investigation on the quantum well structure of a GaAs/Al0.3Ga0.7As superlattice grown on a misoriented substrate A detailed photoluminescence study of a deep broadband emission as a function of the dopant concentration is conducted in molecular-beam-epitaxy-grown silicon-doped Alo.3Gao.7As single layers. The deep broadband which is c()rrelated to the Si concentration consists of several emissions among which three are suggested to be due to different Si C()mplexes. The effects of annealing the samples contributed immensely to this investigation.A model to explain the direct and indirect participations of Si,<\s in the formation of Si complexes during heat treatment is proposed. The photoluminescence is complemented by the HaH-effect, capacitance, and secondary-ion-mass spectroscopy measurements.[N] = [Nd -Nal (donor minus acceptor concentration, respectively), was determined. The crucial point about this alpresent address;

InAs quantum dot structures grown on InGaAlAs have been investigated for midinfrared photodetection. Intraband photocurrent and absorption measurements, together with a full three-dimensional theoretical modeling revealed that a bound-to-bound optical transition, where the final state is about 200meV deep below the conduction band continuum, is responsible for the photogenerated current. The reported results strongly suggest that an Auger process plays a fundamental role in generating the observed intraband photocurrent. Photoluminescence and interband photocurrent spectra of the same structures further support the reached conclusions.

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