Metal–insulator–semiconductor (MIS) structures based on HgCdTe were fabricated after various stages of pn junction formation using As+ implantation and activation annealing. The energy of As+ ions ...was 200 keV with the fluence of 1014 cm−2. Heteroepitaxial HgCdTe films with near-surface graded-gap layers were grown by molecular beam epitaxy (MBE) on silicon substrates. It was shown that the electron concentration in the near-surface semiconductor layer increases after implantation to values of about 1017 cm−3, and after implantation and annealing in the near-surface semiconductor layer, a p+ layer appears with a hole concentration of more than 1.5 × 1018 cm−3. The generation rate of minority charge carriers in the space charge region after implantation is low, which indicates a low defectiveness of the thin near-surface MBE HgCdTe layer. After implantation and annealing, the generation rate increases significantly, which may be due to high defectiveness near the interface between Al2O3 and MBE HgCdTe. Dopant profiles were constructed in the near-surface HgCdTe layers after various technological procedures. It was shown that after implantation in films, the dopant concentration increases with distance from the interface to the depth of 0.1 μm.
•Surface HgCdTe properties were modified by As implantation and thermal annealing.•Metal–insulator–semiconductor structures were created and their admittance studied.•Concentration profiles in HgCdTe after various procedures were determined.•After As implantation, a low-defect layer appears near the interface HgCdTe-Al2O3.•Activation annealing leads to a decrease in the density of slow states.
Metal–insulator–semiconductor structures based on HgCdTe are grown by molecular-beam epitaxy. Near-surface graded-gap layers with a high CdTe content are inserted on both sides of the epitaxial ...HgCdTe film. The capacitance–voltage characteristics of these structures are studied experimentally. The main characteristics of these graded-gap HgCdTe structures are determined taking into account the effect of the non-uniform composition of the near-surface layers on the measured parameters. The capacitance–voltage characteristics of the graded-gap HgCdTe structures with various insulators are examined and the densities of surface states, densities of fixed and mobile charges are evaluated. The properties of the interface for CdTe grown in situ are found to be fairly good. We found that for structures based on HgCdTe–CdTe typical of very low density of mobile charges, the density of fixed charge does not exceed a 5.5×1010cm−2.
► The metal–insulator–semiconductor structures based on HgCdTe were studied. ► A method is proposed for investigation of these graded-gap structures. ► The properties of the interface HgCdTe with some insulators were investigated. ► The properties of the interface for CdTe are found to be fairly good.
In this work the results of the experimental investigation of the influence of the high-frequency nanosecond volume discharge in atmospheric pressure air on the electrophysical properties of ...epitaxial HgCdTe films are presented. Analysis of magnetic-field dependences of the Hall coefficient have shown that in the near-surface region of the material a high-conductivity n-type layer is formed as a result of irradiation. It is shown that relaxation of the values of the electrophysical parameters of the epitaxial films is observed after the irradiation. The supposition is made that the obtained experimental results may be explained by the formation of thin dielectric oxide film at the surface of the irradiated material, containing built-in fixed and mobile positive charge.
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•The influence of volume discharge on properties of HgCdTe films is investigated.•The magnetic-field dependences of Hall coefficient are considered.•The relaxation of values of electrophysical parameters of samples is observed.•The model of change of electrophysical parameters of HgCdTe films is proposed.
Results of the Hall-effect studies of surface properties of n–type HgCdTe films modified with arsenic ion implantation and thermal annealing are reported on. A complete annihilation of ...implantation-induced extended defects (dislocation loops), quasi-point defects and related donor centers was observed as a result of a two-stage arsenic activation annealing. A high degree of activation of implanted arsenic was achieved with the annealing. In some cases, the annealing was found to lead to the modification of the properties of the ‘base’ layers not affected by implantation due to activation of uncontrolled acceptor defects and resulting changes in the degree of electrical compensation.
•Modification of the surface of HgCdTe films with arsenic implantation and annealing was studied.•Annealing was shown to annihilate structural defects induced by implantation.•High degree of activation of arsenic as a result of post-implantation annealing was achieved.•Activation of residual acceptor impurities by post-implantation annealing was discovered.
The capacitive characteristics of metal–insulator-semiconductor (MIS) structures based on the compositionally graded Hg
1−x
Cd
x
Te created by molecular beam epitaxy have been experimentally ...investigated in a wide temperature range (8–77 K). A program has been developed for numerical simulation of ideal capacitance–voltage (C–V) characteristics in the low-frequency and high-frequency approximations. The concentrations of the majority carriers in the near-surface semiconductor layer are determined from the values of the capacitances in the minima of low-frequency C–V curves. For MIS structures based on
p
-Hg
1−x
Cd
x
Te, the effect of the presence of the compositionally graded layer on the hole concentration in the near-surface semiconductor layer, determined from capacitive measurements, has not been established. Perhaps this is due to the fact that the concentration of holes in the near-surface layer largely depends on the type of dielectric coating and the regimes of its application. For MIS structures based on
n
-Hg
1−
x
Cd
x
Te (
x
= 0.22–0.23) without a graded-gap layer, the electron concentration determined by the proposed method is close to the average concentration determined by the Hall measurements. The electron concentration in the near-surface semiconductor layer of the compositionally graded
n
-Hg
1−
x
Cd
x
Te (
x
= 0.22–0.23) found from the minimum capacitance value is much higher than the average electron concentration determined by the Hall measurements. The results are qualitatively explained by the creation of additional intrinsic donor-type defects in the near-surface compositionally graded layer of
n
-Hg
1−
x
Cd
x
Te.
Dark currents in medium-wave
nBn
structures based on HgCdTe grown with the aid of molecular beam epitaxy on the (013) GaAs substrates are studied. The passivation of the surface of the side walls of ...the mesastructures is performed using Al
2
O
3
films formed by plasma atomic layer deposition. It is shown that the volume component of the dark current dominates in the
nBn
structures with a composition in the barrier layer of 0.84. The activation energy of the current is close to the band gap of the absorbing layer. Comparison of the experimental results with the results of the Rule07 empirical model shows that the diffusion limitation of the dark current takes place in the fabricated structures in a temperature interval of 180–300 K. The results indicate that the molecular beam epitaxy of HgCdTe on alternative substrates is a promising method for fabrication of unipolar barrier detectors for a spectral interval of 3–5 µm.
The paper, which consists of two parts, considers in detail the method of discrete mobility spectrum analysis (DMSA) proposed by the authors as well as its application to determine the parameters of ...charge carriers in CdHgTe. The first part of the work was a brief review of the existing methods for analyzing the field dependences of the Hall coefficient and conductivity in structures with a multi-carrier spectrum of charge carriers. In the second part of the work, the physical properties of the mobility spectrum envelope in the mobility spectrum analysis (MSA) method are analyzed and the main idea, features, and algorithm of the DMSA method are presented. On the example of studying the electrical properties of numerous samples of CdHgTe epitaxial films, the high sensitivity of the DMSA was confirmed. Using DMSA, we analyzed a number of dependences of the conductivity tensor components σ
xx
and σ
xy
on the magnetic field B, available in the literature, and compared the results of the analysis with those obtained with other methods.
Two-dimensional materials have become one of the central research topics of scientists around the world after the production of graphene – a monatomic layer of carbon. Currently, two-dimensional ...crystals are among the most promising materials for next-generation nanoelectronics and photonics. The exploration of the feasibility of 2D materials devices causes a deeper insight into the physical properties of these new materials and provides a starting point for the development of a number of important practical areas. Over the past few years, researchers have been paying increased attention to graphene-like materials of group IVA elements, such as silicene (Si), germanene (Ge), stanene (Sn), and plumbene (Pb). Experimental production and study of the unique properties of two-dimensional monatomic layers of carbon, silicon, germanium, tin, and lead on various substrates created the prerequisites for the development of new generation devices based on them. The wide possibilities for controlling their exotic electronic, magnetic, and optical properties through the choice of the substrate, the design and geometry of the two-dimensional layer, as well as by controlling the magnitude of elastic stresses, have made them a dominating topic for studying in the field of nanotechnology and materials sciences. This paper reviews the latest advances in growing silicene, germanene, stanene, and plumbene using epitaxial methods. Growth technologies for creation of high-quality two-dimensional structures of large area required for promising instrumentation area are considered in more detail.
Metal–insulator–semiconductor structures based on HgCdTe are grown by molecular-beam epitaxy. Near-surface graded-gap layers with high CdTe content are formed on both sides of the epitaxial HgCdTe ...film. Photoelectrical characteristics of these structures are studied experimentally and theoretically. For structures based on n-Hg1−xCdxTe (x=0.21–0.23), the formation of a near-surface graded-gap layer leads to an increase in the differential resistance of the space charge region due to the suppression of tunneling. The temperature dependences of the differential resistance calculated with account to different mechanisms of generation of minority charge carriers are similar to the experimental dependences of the photoelectromotive force.
•The metal–insulator–semiconductor structures based on HgCdTe were studied.•Photoelectrical properties of such structures were investigated.•Mechanisms of generation of minority carriers were studied.•Creation of near-surface graded-gap layers suppresses tunneling.
We analyze the current state of research in the field of creating unipolar semiconductor barrier structures based on various materials for infrared photodetector arrays, which make it possible to ...reduce the dark currents and thereby improve the threshold characteristics and ensure operation at high cooling temperatures. The main ways of minimizing a barrier for holes in the valence band are considered by the example of a photosensitive structure based on the
n
-CMT layer. It is shown that the
nBn
barrier structures are an alternative for creating photodiode sensing matrices for the mid- and far-infrared photodetector arrays.
