Articles you may be interested inElectron emission properties of relaxation-induced traps in InAs/GaAs quantum dots and the effect of electronic band structure Combined optical and electrical studies of the effects of annealing on the intrinsic states and deep levels in a self-assembled InAs quantum-dot structure J. Appl. Phys. 100, 043703 (2006); 10.1063/1.2234817Conduction-band offset in a pseudomorphic GaAs/In 0.2 Ga 0.8 As quantum well determined by capacitance-voltage profiling and deep-level transient spectroscopy techniques
We demonstrate normal incidence infrared imaging with quantum dot infrared photodetectors using a raster-scan technique. The device heterostructure, containing multiple layers of InAs/GaAs self-organized quantum dots, were grown by molecular-beam epitaxy. Individual devices have been operated at temperatures as high as 150 K and, at 100 K, are characterized by λpeak=3.72 μm, Jdark=6×10−10 A/cm2 for a bias of 0.1 V, and D*=2.94×109 cm Hz1/2/W at a bias of 0.2 V. Raster-scan images of heated objects and infrared light sources were obtained with a small (13×13) interconnected array of detectors (to increase the photocurrent) at 80 K.
Ultrafast differential transmission spectroscopy with a resonant pump reveals evidence of electronic tunneling among the excited levels of vertically aligned In 0.4 Ga 0.6 As self-organized quantum dots. This evidence of tunneling is observed as a rapid spectral redistribution of electrons within a few hundred femtoseconds of optical excitation. Measurements show that this spectral spread is independent of carrier density and, therefore, indicate that carrier-carrier scattering is not the main mechanism for carrier redistribution. Instead, electronic tunneling is responsible for the interdot coupling; tunneling rate calculations agree reasonably with the experiment, supporting this conclusion.
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