A prototype of a metal–insulator–semiconductor field-effect transistor based on PbSnTe:In/(111)BaF2 film with an Al2O3 gate dielectric was designed for the first time. With the gate voltage applied in the range – 7.7 V < Ugate < +7.7 V the relative modulation in the drain-source current Ids/Ids attained near five-fold change at T = 4.2 K. When illuminated with rela-tively low (~100 photon/s) fluxes, negative photoconductivity was detected accompanied with a decrease in Ids by ~104 times and a simultaneous decrease in Ids by ~103 times or even more. The estimated detectivity was about 71016 cmHz0.5W-1 at a wavelength  about 25 micron with the accumulation time about 0.5 s. A qualitative model is discussed which assumes the ex-istence of deep traps and a photo-capacitance effect.

Changes in the structure and elemental composition of the surface of the epitaxy-ready InP(001) substrate in an As flux in ultrahigh vacuum are studied in situ by the reflection high-energy electron diffraction (RHEED) technique. It is shown that, during annealing of the oxide layer at the surface, an InP 1 – x As x layer is formed as a result of the substitution of phosphorus by arsenic. The dependence of the degree of substitution on the annealing temperature and time is established. The degree of the substitution of phosphorus by arsenic in the surface layer is 7% at the annealing temperature 480°C and, reaches 41% at the temperature 540°C. The annealing time influences the degree of substitution only slightly.

The surface topology of epitaxial films of lead tin telluride solid solution (including with In additive, Pb1 – xSnxTe:In) has been examined using atomic force microscopy. The films have been grown on BaF2(111) single-crystal substrates and on a CaF2/BaF2 buffer layer covering a Si(111) wafer. It has been shown that the relief statistical parameters depend on film growth conditions and the incorporation mechanism of indium, an excess amount of which has been detected on the surface by ex situ XPS.

An atomically clean and structurally ordered surface of the CdTe layer of a (013)-oriented GaAs/ZnTe/CdTe substrate after storage in air is obtained by treatment in isopropyl alcohol saturated with hydrochloric-acid vapors, with subsequent thermal annealing in ultrahigh vacuum. It is shown that chemical treatment of the CdTe surface results in the removal of native oxides and in enrichment of the surface with an elemental Te layer. During heating in vacuum, two stages of change in the state of the surface (at ~125 and ≤250°C) are observed. At the temperature T > 250°C, elemental tellurium is desorbed, and a Te-stabilized (1 × 1) CdTe(013) structure is formed.

We report experimental study of the transformation of the epi-ready InP(001) surface during annealing in an arsenic flux. Using the RHEED method, it was shown that an InP1−xAsx layer is formed on the surface. The amount of arsenic substitution for phosphorus at different annealing temperatures was determined, which is 7% at an annealing temperature of 480◦C and increases to 41% with an increase in the annealing temperature to 540◦C. The annealing time has little effect on the degree of substitution.

In this work, atomically clean and structurally ordered surface of CdTe epitaxial layer after storage in air by treatment in isopropyl alcohol saturated with vapors of hydrochloric acid, and further temperature heating in an ultrahigh vacuum, was obtained. CdTe surface chemical treatment results in the removal of native oxides and surface enrichment with elemental tellurium. Heating in vacuum leads to the tellurium desorption and the appearance of a Te-stabilized CdTe surface. During heating in vacuum, two stages of surface state change are observed (~125°С and ≤250°С). At Т>250°С, elemental tellurium is desorbed and a Te-stabilized structure (1x1) CdTe(013) is formed.

In present work, the effect of Pb1-xSnxTe In In (1 1 1) surface in HCl-isopropanol (HCliPA) solution led to removal of native oxides and surface enrichment by elemental tellurium of several nm thickness. Subsequent anneals in vacuum led to desorption of elemental tellurium and revealing (1x1) surface structure. We present angle resolved photoemission spectroscopy (ARPES) measurements of the surface states on chemically prepared (1 1 1) oriented MBE-grown films of Pb1-xSnxTe, a three-dimensional topological crystalline insulator (TCI). The surface states with Dirac-like dispersion at Gamma in the surface Brillouin zone were detected. The dark current and photocurrent were found in strong dependence on the surface chemical procedure and composition. The relative simplicity of the preparation technique is encouraging, and suggests a clear path for future investigations of TCI states on alternative surface orientations in (Pb,Sn)Te solid solutions and applied aspects of TCI research.

•The chemical treatment of Pb1-xSn xTe (111) films with HCl-iPA solution removed native oxides.•Further annealing in vacuum led to the formation of structurally ordered Pb1-xSn xTe (111)-(1x1) surface.•ARPES demonstrated the surface topological states of a crystalline insulator with Dirac dispersion.•A significant effect of the HCl-iPA treatment on electrophysical properties was demonstrated.

The topology of the surface of epitaxial films of lead tin telluride solid solution, including those with the addition of indium (Pb1-xSnxTe:In), grown on single-crystal BaF2 (111) substrates and a CaF2/BaF2 buffer layer on Si (111) was studied by atomic force microscopy. It is shown that the characteristic statistical indicators of the relief are due to the peculiarities of film growth and the mechanism of incorporation of Indians, the excess content of which was registered on the surface ex situ by X-ray photoelectron spectroscopy.

The dependence of the photoconductivity sign on the bias voltage, intensity and duration of illumination was studied in PbSnTe:In films in the space charge limited current regime. The role of traps with a complex energy spectrum, including the surface traps, in the observed effects is discussed

The dependence of the photoconductivity sign on the bias voltage, intensity, and duration of illumination is studied for PbSnTe:In films in the space-charge-limited current regime. The role of traps (including surface ones) with a complex energy spectrum in the effects under observation is discussed.

High-resistance Pb1 –xSnxTe〈In〉 layers grown by molecular beam epitaxy on BaF2(111) substrates with compositions close to band inversion have been investigated. The I–V characteristics and relaxation dependences of the photocurrent of the structures in dependence on the chemical surface treatment and subsequent exposure of the samples in air have been examined. It has been observed that the characteristics significantly transform depending on the physicochemical surface state. It has been found that the chemical surface treatment in the hydrochloric acid solution in isopropyl alcohol leads to an increase in the current by up to four orders of magnitude with the subsequent recovery of the I–V characteristics upon exposure of the samples in air for several days.

AbstractHigh-resistance Pb_1 –_ x Sn_ x Te〈In〉 layers grown by molecular beam epitaxy on BaF_2(111) substrates with compositions close to band inversion have been investigated. The I–V characteristics and relaxation dependences of the photocurrent of the structures in dependence on the chemical surface treatment and subsequent exposure of the samples in air have been examined. It has been observed that the characteristics significantly transform depending on the physicochemical surface state. It has been found that the chemical surface treatment in the hydrochloric acid solution in isopropyl alcohol leads to an increase in the current by up to four orders of magnitude with the subsequent recovery of the I–V characteristics upon exposure of the samples in air for several days.

Abstract00-The kinetics of the formation and thermal decomposition of a two-dimensional SiN-(8 × 8) nitride layer on a Si(111) surface is studied. The SiN-(8 × 8) structure is a metastable intermediate phase formed during the nitridation of silicon before the formation of a stable amorphous Si_3N_4 phase. Studying the SiN-(8 × 8) structure by scanning tunneling microscopy shows its complex structure: it consists of an adsorption (8/3 × 8/3) phase, with the lateral period 10.2 Å, and a honeycomb structure with a ~6 Å side of a hexagon that is turned 30° with respect the adsorption phase. The band gap of the SiN-(8 × 8) phase is measured and found to be ~2.8 eV, which is smaller compared to the band gap of the β-Si_3N_4 crystal phase 5.3 eV. The interplanar spacings in the (AlN_3)/(SiN)_2 structure on the Si(111) surface are measured. The spacings are 3.3 and 2.86 Å in SiN and AlN, respectively. Such interplanar spacings are indicative of weak van der Waals interaction between the layers. A model of the SiN-(8 × 8) structure as a flat graphene-like layer is suggested. The model is consistent with the diffraction and microscopy data.

00-The kinetics of the formation and thermal decomposition of a two-dimensional SiN-(8 × 8) nitride layer on a Si(111) surface is studied. The SiN-(8 × 8) structure is a metastable intermediate phase formed during the nitridation of silicon before the formation of a stable amorphous Si3N4 phase. Studying the SiN-(8 × 8) structure by scanning tunneling microscopy shows its complex structure: it consists of an adsorption (8/3 × 8/3) phase, with the lateral period 10.2 Å, and a honeycomb structure with a ~6 Å side of a hexagon that is turned 30° with respect the adsorption phase. The band gap of the SiN-(8 × 8) phase is measured and found to be ~2.8 eV, which is smaller compared to the band gap of the β-Si3N4 crystal phase 5.3 eV. The interplanar spacings in the (AlN3)/(SiN)2 structure on the Si(111) surface are measured. The spacings are 3.3 and 2.86 Å in SiN and AlN, respectively. Such interplanar spacings are indicative of weak van der Waals interaction between the layers. A model of the SiN-(8 × 8) structure as a flat graphene-like layer is suggested. The model is consistent with the diffraction and microscopy data.

Исследованы пленки PbSnTe:In с длинноволновой границей чувствительности свыше 20 мкм и низкой проводимостью без освещения. Проведено сравнение спектральных зависимостей фотопроводимости, полученных при различных температурах с использованием фурье-спектрометра, с составом пленок, определенным методом рентгеновского микроанализа. Обнаружена немонотонная зависимость длинноволнового края фоточувствительности от температуры, которая объясняется комбинацией температурной зависимости ширины запрещенной зоны PbSnTe и эффекта Бурштейна-Мосса, дающего наибольший вклад в измерения при низких температурах из-за большого времени жизни неравновесных носителей заряда. Показано, что различия в значениях ширины запрещенной зоны, определяемых из измеренного состава и температурных зависимостей длинноволнового края чувствительности, могут быть связаны с неоднородностью состава пленок, получаемых методом молекулярно-лучевой эпитаксии. DOI: 10.21883/FTP.2017.11.45114.29

PbSnTe:In films with a long-wavelength sensitivity limit of over 20 μm and low “dark” conductivity are studied. The spectral dependences of the photoconductivity obtained at different temperatures using a Fourier spectrometer are compared with data on the film composition determined by X-ray microanalysis. The established nonmonotonic temperature dependence of the long-wavelength sensitivity limit is attributed to the combination of the temperature dependence of the PbSnTe band gap and the Burstein–Moss effect making the largest contribution to low-temperature measurements due to the long lifetime of excess charge carriers. It is shown that the difference between the band-gap values determined from the measured composition and temperature dependences of the long-wavelength sensitivity limit can be related to the inhomogeneity of the composition of the films grown by molecular beam epitaxy.

The PbTe and Pb 1 − x Sn x Te films, both undoped and doped with indium, are studied by Raman spectroscopy. It is found that the film surface changes during spectra recording. From comparative analysis of the data obtained in the study and those reported in publications, it is inferred that the 90, 117, and 138 cm −1 peaks correspond to the scattering of light at tellurium or tellurium-oxide precipitates. It is established that these peaks appear in the spectra of Pb 1 − x Sn x Te films and epitaxial PbTe films only when doped with indium. The 180-cm −1 peak is observed in the spectra of all of the samples and not attributed to the plasmon-phonon mode. The nature of the 180-cm −1 peak is still not completely understood.

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.

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.