S. P. Suprun

Injection currents in narrow-gap (Pb1−xSnxTe):In insulators

The low-temperature current-voltage characteristics of narrow-gap (Pb1−xSnxTe):In have been studied experimentally and calculated for a wide range of electric fields. It is shown that the obtained data are satisfactorily described in terms of a space-charge-limited current model in the presence of traps. The concentration and energy depth of the traps have been estimated.

Low-temperature recrystallization of Ge nanolayers on ZnSe

The in situ X-ray photoelectron spectroscopy observation of low-temperature recrystallization of an amorphous Ge layer deposited on a ZnSe film at room temperature is reported. It is shown that the experimentally measured shifts of the Ge 3d core level are consistent with the changes observed in the crystal structure of the layer by the high-energy electron diffraction technique in the reflection mode of measurements. The shifts can be attributed to successive nanometer-scaled structural changes in the Ge layer with increasing temperature.

Raman scattering of light by optical phonons in Si-Ge-Si structures with quantum dots

Raman scattering of light by optical phonons in Si-Ge-Si structures with pseudomorphic germanium quantum dots has been investigated. Resonance amplification of the scattering intensity on E0 (Γ7−Γ8) transitions has been observed. It is shown that as a result of the formation of the layer of germanium quantum dots, the resonance energy is ∼0.3 eV higher than in the two-dimensional case.

Thin-film PbSnTe:In/BaF2/CaF2/Si structures for monolithic matrix photodetectors operating in the far infrared range

We report for the first time on the creation of 288 × 2 matrix photodetectors with an element size of 25 × 25 μm based on PbSnTe:In/BaF2/CaF2/Si structures and present their threshold characteristics. The detection ability of about 90% elements ranges from 7.2 × 1012 to 8.7 × 1012 cm Hz0.5/W at T = 21.2 K. The proposed technology opens ways to the creation of monolithic matrix photodetectors operating in the far-IR range.

Formation of the GaAs-Ge heterointerface in the presence of oxide

The data of the X-ray photoelectron spectroscopy and reflection high-energy electron diffraction studies of the formation of the GaAs-Ge heterointerface under incomplete removal of all oxide phases from the GaAs substrate surface are presented. It is shown that the combination of the processes of final Ga2O desorption and Ge deposition allows one to avoid the evaporation of As and the stoichiometry distortion near the interface.

Epitaxial growth of ZnSe on GaAs with the use of the ZnSe compound as the source

Processes of the molecular-beam epitaxy of submicron layers of ZnSe on GaAs (001) substrates with the use of the ZnSe compound as the source have been investigated depending on the initial state of the substrate surface and its temperature. It is shown that after the formation of the heterointerface the “excess” Ga remains on the surface of the growing film, determining, at temperatures above 250°C, the rate of its growth. According to the experimentally measured spectra of low-temperature luminescence, the optimum temperature of obtaining layers by this method is 240°C.

Effect of an electron beam on CaF2 and BaF2 epitaxial layers on Si

Atomically smooth CaF2 and BaF2 layers have been sequentially grown on Si(111) substrates by molecular beam epitaxy. Pore macrodefects have been revealed at the points of the action of an electron beam from a diffractometer when analyzing the crystal structure of the surface during the growth with the subsequent observation using atomic force microscopy. The formation of these macrodefects is associated with the decomposition of fluorides by high-energy electrons, which is accompanied by the desorption of fluorine and the drift current of positive ions from the electron charge drains.

Giant negative photoconductivity of PbSnTe:In films with wavelength cutoff near 30 μm

Experimental results on the photoconductivity dynamics in PbSnTe:In films with a high SnTe content and corresponding fundamental absorption edge near 30 μm at liquid helium temperatures are reported. The possible causes for the giant (over two orders of magnitude) negative photoconductivity of the samples are discussed.

Effect of the surface on transport phenomena in PbSnTe:In/BaF2 films

The effect of the surface on the I–V characteristics of PbSnTe:In film-based structures is investigated in zero magnetic field and in a magnetic field of B ≤ 4 T with different orientations, including in the mode of current limited by space charge. Analysis of the features in the experimental data obtained at different magnetic-field directions and upon layer-by-layer etching of the films shows that the contributions of the free film surface and interface with the substrate to transport phenomena are significantly different and can be caused by a difference in the parameters of localization centers near these surfaces.

Study of the Photoelectric Properties of Ge Quantum Dots in a ZnSe Matrix on GaAs

The current-voltage (I–V) and spectral characteristics of a photocurrent are studied at T=4.2 and 300 K for an unstrained GaAs/ZnSe/QD-Ge/ZnSe/Al structure with tunneling-transparent ZnSe layers and Ge quantum dots (QDs). Features such as the Coulomb staircase were observed in I–Vcharacteristics at room temperature and in the absence of illumination. An energy-band diagram of the structure is constructed based on an analysis of the experimental data. In the GaAs/ZnSe/QD-Ge/ZnSe/p-Ge transistor structure with a p-Ge channel and Ge-QD floating gate, the total current of the channel both increased and decreased under exposure to light with various spectra. These variations in channel current are associated with the capture of a positive and negative charge at QDs during different optical transitions. The charge accumulation changes the state of a channel at the heterointerface from depletion to inversion and either decreases or increases the total current.