Colloidal nanocrystals (quantum dots (QDs)) of mercury selenide have been synthesized and the effect of size quantization on their basic properties has been investigated. The current-voltage characteristics of single QDs (less than 10 nm) had features in the form of separate regular peaks and quasi-periodic current oscillations with voltage intervals (0.1–0.2) V. The observed features were explained in the models of size quantization and Bloch oscillations. The absorption spectra in the range up to 25 μm had eight certain peaks, including five – interband and intraband transitions and three – with energies (145–215) meV, which are explained as intraresonant. Calculations show that it is possible to have IR photosensitivity in the wavelength range up to 40 μm.
In the lead sulfide nanoparticles-based layers deposited from alcohol suspensions, analysis of the current-voltage characteristics made it possible to establish the basic mechanism of electron transport. Previously, using optical measurements in the range of 3500 nm, it was shown that the organic component in such layers was practically absent. When exposed to wide range radiation corresponding to the “transparency window” of the atmosphere of 8000–14000 nm, a current change in PbS nanodust was detected, where, as previously shown, absorption on free charge carriers can occur.
For quantum-size particles of the InSb, PbS, HgSe, CdSe semiconductors, a model of competition of dimensional quantum restrictions and blocking with a single-electron current and Coulomb restriction, as well as heating electrons with an electric field of the light wave, is proposed. This made it possible to explain the highly multiplicity (up to two orders of order) of a change in photoconductivity observed in conditions of tunnel conductivity, and in the conditions of the сonfinition - the absence of inter-zone and inter-level photoconductivity. The resonant current peaks of quantum conductivity observed on the V-I characteristics when irritating with light of any wavelength (in the interval of 0.4–1.2 µm) are reset or shifted towards smaller voltage values. The energy minimum recorded in this case is estimated as 100 meV. The results can be useful in resolving issues of application in uncooled IR detectors, including single-photon registration.
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