Articles you may be interested inImproved performance of HgCdTe infrared detector focal plane arrays by modulating light field based on photonic crystal structure
Previously reported data on photoluminescence quenching in ionbeam irradiated silicon dioxide layers with embedded silicon nanocrystals were used to analyze the exciton lifetime in such systems versus the quenched fraction of nanocrystals. Estimates of the characteristic time of exciton hopping between adjacent nanocrystal grains, the length of excitonic wavefunction decay into the dielectric, and the cross-section of exciton recombination at deep-level centers introduced by the irradiation into the SiO 2 matrix are given.
The temperature dependence of the photoluminescence intensity in Si3+xN4:H films grown on Si substrates in a PECVD process held at temperatures 100 and 380oC was analyzed versus the film stoichiomery. The film stoichiometry parameter x was varied in the range x = 0.08 to 3.7 via varying the NH3/SiH4 flow ratio (0.5 to 5). According to Raman scattering data, the films contained amorphous Si nanoclusters, whose sizes increased with x and substrate temperature. For the first time, the involvement of two different processes in the nonradiative relaxation of excitations optically generated in the system under study has been demonstrated. These processes were tentatively identified as the thermal dissociation of nanocluster-bound excitons and their nondissociative migration to nonradiative sites in neighboring Si nanoclusters. The activation energies and the frequency factors of the two processes were shown to be consistent with the quantum confinement model for the amorphous Si nanocluster related photoluminescence.
The lateral diffusion of minority charge carriers in the photosensitive films of photovoltaic HgCdTe infrared focal plane array (IR FPA) detectors with a continuous (without mesa insulation of the diodes) absorber layer was experimentally studied and analyzed. The experimental study was performed using the spot-scan technique, implemented by scanning a narrow strip-shaped illumination spot with a selected FPA diode at various levels of diode photocurrents in the detector. The local diffusion lengths of the charge carriers in the film regions beneath and outside the FPA diodes were estimated. The values obtained for the bulk diffusion length of minority carriers in the HgCdTe material of the examined middle-wave and long-wave IR FPA detectors were found to be in good agreement with previously reported data. Moreover, the estimated local diffusion length of minority carriers in the film region beneath the back-biased photodiodes proved to be consistent with a theoretical estimate of this length.
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