The purpose of this paper was investigating the effect of volume nanosecond discharge in air at atmospheric pressure on the electro-physical properties of the HgCdTe (MCT) epitaxial films grown by molecular beam epitaxy. Hall measurements of electro-physical parameters of MCT samples after irradiation have shown that there is a layer of epitaxial films exhibiting n-type conductivity that is formed in the near-surface area. After more than 600 pulses of influence parameters and thickness of the resulting n-layer is such that the measured field dependence of Hall coefficient corresponds to the material of n-type conductivity. Also it is shown that the impact of the discharge leads to significant changes in electro-physical characteristics of MIS structures. This fact is demonstrated by increase in density of positive fixed charge, change in the hysteresis type of the capacitance-voltage characteristic, an increase in density of surface states. The preliminary results show that it is possible to use such actions in the development of technologies of the controlled change in the properties of MCT.
Review of the authors' works devoted to research of properties of high-temperature gas mixtures and advancement of methods of a remote diagnosis of their optical and physical characteristics is presented. Results of the formation of the informational resource on mathematical, spectroscopic, software and hardware support of passive and active remote sensing techniques of gas-aerosol media are discussed.
Results of research electrophysical and photoelectric properties of HgCdTe photoconductive structures grown by method molecular beam epitaxy under influence of background radiation are submitted. Strong dependence of photoconductivity and carriers lifetime for a level of background radiation (for change aperture angle of diaphragm), which come to an agreement with results of calculation for the Auger mechanism of recombination are represented.
The electro-physical and photo-electrical properties of the HgCdTe/SiO2/Si3N4 and HgCdTe/anodic-oxide film MIS structures is experimentally studied. The heteroepitaxial graded-band films Hg0.78Cd0.22Te were produced on the GaAs substrates by molecular-beam epitaxy. It was established of features of electrical properties were related with conduction type of the semiconductor and to the presence of near-surface graded-band layers. The test measurements of the electro-physical and photoelectric performances of MIS-structures in base of graded-band HgCdTe are held and the following parameters are found: resistances of volume, voltage of flat bands, densities of mobile and fixed charges, spectrums of surface states. It is shown that low-temperature double insulator SiO2/Si3N4 is perspective for passivation of surface of focal plane arrays in base of HgCdTe-photodiodes.
In the paper experimental results on boron implantation of the CdxHg1-xTe epilayers with various composition near surface of the material are discussed. The electron concentration in the surface layer after irradiation vs irradiation dose and ion energy are investigated for range of doses 1011 - 3•1015 cm-2 and energies of 20 - 150 keV. Also the results of the electrical active defects distribution measurement, carried out by differential Hall method, after boron implantation are represented. Consideration of the received data shows, that composition gradient influence mainly on the various dynamics of accumulation of electric active radiation defects. The electric active defects distribution analysis shows, that the other factors are negligible.
The surface microrelief of CdHgTe layers grown by molecular-beam epitaxy (MBE) method has been studied by means of atomic-force microscopy. A periodic surface microrelief in the form of an ordered system of extended waves with the characteristic period 0.1-0.2 μm has been detected on epilayers grown at increased temperatures. Angular dependencies of the conductivity at 77 K have been measured and the conductivity anisotropy has been detected with a minimum in the direction transverse to microrelief waves. A feature of the transmission system and the spectrum change after film annealing are observed. It is assumed that walls growing in the direction from the substrate to the surface are formed under microrelief waves slopes. Such structure can cause the observed feature of the transmission spectrum if the adjacent walls have different composition. In this work a calculation of spectral characteristics taking into account the influence of variable-gap composition and nonuniformity of the composition through the depth has been carried out.
The first results on a radiation stability investigation of mercury cadmium telluride (MCT) films, grown by molecular beam epitaxy (MBE) are represented. The samples were irradiated by high energy electron beams and gamma rays. Electrophysical and photoelectric parameters of MCT epilayers were measured. Volume material was measured too for the checking with MBE-grown one. MBE epifilms were irradiated on a pulsed electron accelerator with electron energy 1-2 MeV and current density less than 1 μA/cm2 for several fluences. Also MCT epitaxial heterostructures were irradiated by Co60 gamma rays. The same experiments were carried out for volume material. The analysis of dependence of Hall coefficient and conductivity from temperature and magnetic field (B) for p- and n- type samples was made. The irradiation of epilayers and volume MCT in the investigated range of irradiation fluences does not give both creation of electrical active damages in high concentrations and reconstruction of initial defects. Thus, MBE films of MCT have the high radiation stability to an electron and gamma irradiation. The obtained first results allow us to speak about high performance of explored MCT epilayers.
Platinum silicide Schottky barrier detectors (SBD) and HIP-detectors GeSi/Si-based are widely used for application in the infrared spectral range. The increase in cutoff wavelength and responsivity of PtSi-Si photodevices is possible by formation of heavily-doped thin layer near to the semiconductor surface. The cutoff wavelength of HIP-detectors GexSi1-x/Si-based depends on x and concentration of boron in GeSi. In this report, the threshold properties of these detectors are considered. The dependencies of spectral detectivities and NETD from cutoff wavelength are calculated for various parameters of SBD and HIP-detectors. It is shown that optimal NETD of a SBD and HIP-detectors is possible for certain cutoff wavelength and temperature of detectors and depends on storage capacity. Also opportunity of formation of heavily-doped nanolayer in SBD detectors used by short-pulse recoil implanation of boron was studied.
Platinum silicide Schottky barrier detectors are widely used for application in the medium infrared wavelength region. The increase of cutoff wavelength and responsivity of PtSi-Si photodevices is possible by formation of highly-doped thin layer near to the semiconductor surface. We propose for this aim to form highly-doped nanolayer in p-Si by recoil implantation of boron. It is experimental established that profile of impirity distribution in surface layer is exponential. The doping concentration at the silicide/silicon interface is 1018 - 1020 cm-3 and thickness of surface layer is 8 - 12 nm. We have calculated the spectral, threshold, and noise characteristics of p-Si-PtSi photodetectors with highly-doped surface layers produced by molecular-beam epitaxy and short-pulse dopant implantation by a recoil method.
The development of Schottky barrier technology for creation of IR-photodetectors is caused by reduction of a potential barrier height used by formation of heavily-doped thin layer near to the semiconductor surface. We propose for this aim to form heavily-doped nanolayer in p-Si by recoil implantation of boron. Boron nm-thick film was deposited on the Si sample surfaces by cathode sputtering. After that the samples were irradiated by high intensity Al+ beams extracted from pregenerated explosion-emission plasma. The samples are examined by secondary ion mass-spectrometry (SIMS). It is experimental established that profile of impurity distribution in surface layer is exponential. The doping concentration at the silicide/silicon interface is 1018-1020 cm-3 and thickness of surface layer is 8 - 12 nm. The energy band diagrams of a PtSi - p- Si Schottky barrier with high-doped surface layer formed by recoil implantation were calculated for different parameters of barrier. It is shown, that effective barrier heights in PtSi-Si with recoil implantation formed surface 10 nm layer at surface concentration order 1020 cm-3 is reduced to 0.13 eV, corresponding to a cutoff wavelength of 9.5 micrometers . Thus, the cutoff wavelength of the PtSi Schottky infrared detectors has been extended to the long wavelength infrared region by incorporating a p+ doping layer with exponential profile of impurity distribution at the silicide/silicon interface.
The abnormal photo electric properties of MIS structures in base of Si and HgCdTe, such as a significant photo-emf signal in enhancement and drop of the local photo-emf in inversion, were experimentally investigated. It has been established that the reason for the significant photo-emf signal in the state of enhancement and the related features of the photo electric properties of the Si-MIS-structure, is the photosensitivity in the region far from the electrode, associated with non-uniform distribution of electrically active defects in this region. It has also been established that the non-uniformity in surface potential (between the sub-electrode region and the region away from the electrode or between different points in sub-electrode region) may result in a drop of the local photo-emf in the state of inversion. A conclusion has been made that the redistribution of non-equilibrium carriers along the boundary must be taken into account in constructing equivalent circuits of the MIS structures.
The photo electric characteristics of Schottky barriers, created by recoil implantation in silicon, are analyzed. Implantation of boron atoms in silicon samples was made by recoil method, inducing Al ion beams bombardment, with current density 4-10 A/cm2 and 30-150keV energy. A SIMS analysis of obtained structures and calculation of their electric parameters show the opportunity of conducting layers formation, with a thickness of 10 nm and carrier concentration higher than 1018 cm-3.
Parameters of Hg1-xCdxTe epitaxial structures produced by molecular beam epitaxy are presented. Results of measurements of the carrier recombination lifetime, sensitivity and the noise voltage of photosensitive elements have been studied. A high detectivity was obtained over a broad wavelength range.
The angular distribution of the annihilation photons (ADAP) and positron lifetime measurements have been carried out to study of vacancy-type defects in samples of Hg1-xCdxTe (MCT). It was found that ADAP curve parameters for as-grown MCT crystal are very different from ones for low defect samples. The values of the annihilation rate in the bulk state and in the V'Hg trapped state were obtained as 3.55 ns-1 and 3.13 ns-1, respectively. The specific positron trapping rate v was estimated to be 5 (DOT) 10-7 cm3s-1.
The abnormal photoelectric properties of MIS structures, such as a significant photo-emf signal in the state of enhancement and a drop of the local photo-emf in inversion, were investigated with integrated and local photoelectric measurements. It has been established that the reason for the significant photo-emf signal in enhancement and the related features of the photoelectric properties of the structure is the photosensitivity in the region away from the electrode associated with a nonuniform distribution of electrically active defects. It has been demonstrated that the nonuniformity in surface potential (between the subelectrode region and the region away from the electrode (after-electrode region) or between different points in subelectrode region) may result in a drop of the local photo-emf in inversion. A conclusion has been made that the redistribution of nonequilibrium carriers along the boundary must be taken into account in constructing equivalent circuits of actual MIS structures.
The procedure of Rutherford backscattering spectrometry (RBS) is worked out for following goals: firstly, investigation of stoichiometry damages of semiconductor subsurface layer after various methods of treatment; secondly, investigation the depth distribution of the components in semiconductor- insulator transition layer; thirdly, determination of components concentration in anodic oxide and transition layer depth. Taking into account the special features of the narrow- gap semiconductor-insulator structures we chose the optimum ion type and energy, scattering geometry, admission time of spectrum to except the heating, radiation damage and composition stoichiometry variation. With the RBS we have carried out the extensive investigations of influence of surface handling conditions, anode oxidation regimes on the properties of the metal-insulator-semiconductor (MIS) structures on the base of the narrow-gap semiconductors such as HgCdTe (MCT), HgMnTe (MMT) and HgZnTe (MZT) having various compositions and electric parameters.
The composition of subsurface region MZT has been studied using Rutherford backscattering spectroscopy (RBS) ions helium. Interrelation of the electrical properties of MIS structures with the result of RBS have been determinated. It is found that the effective surface charge is connected with composition stoichiometry variation of subsurface region semiconductor.
The results of measurements of lifetime of charge carriers in epitaxial structures based on narrow gap Hg1-xCdxTe, grown by a method molecular-beam epitaxy are resulted at pulsing excitation by radiation on various lengths of waves.
An opportunity of forming heavily doped boron layers in silicon is analyzed in this work for variation of potential barrier height on the metal-semiconductor interfaces. Implantation of boron atoms in silicon samples was made by recoil method, inducing Al ion beams bombardment with current density 4-10 A/cm2 and 30-150 keV energy. An analysis of getting structures by SIMS and calculation of their electric parameters show the opportunity of conducting layers formation with a thickness of 10 nm and carrier concentration more than 1018 cm-3.
The abnormal photoelectric properties of Si-MIS structures, such as a significant photo-emf signal in the state of enhancement and a drop of the local photo-emf in inversion, were investigated with integrate and local photoelectric measurements. It has been established that the reason for the significant photo-emf signal in enhancement and the related features of the photoelectric properties of the structure is the photosensitivity in the region away from the electrode associated with a nonuniform distribution of electrically active defects. It has been demonstrated that the nonuniformity in surface potential may result in a drop of the local photo-emf in inversion. A conclusion has been made that the redistribution of nonequilibrium carriers along the boundary must be taken into account in constructing equivalent circuits of actual MIS structures.
Carrier lifetimes in Hg1-xCdxTe (x equals 0.195 - 0.230) structures grown by molecular beam epitaxy are presented. The carrier lifetimes have been determined from photoconductivity decay after excitation with radiation pulse at various wavelength. It is clearly shown that borders of epitaxial layers influence their photoelectrical properties.
Influence of a weak magnetic field on photo-electric, electrophysical characteristics of MIS - structures is experimentally investigated.Long-term changes of a spectrum of surface states of Si-SiO2-structures, caused by a magnetic field are considered. It is supposed that the reason of a long-term relaxation in Si-SiO2 - structures are a diffusion and reactions of nonequilibrium defects, arising at relaxations of polarization of nuclear spin system, in InSb, InAs the diffusion passes on mechanism of transfer of defect of a type 'broken off connection'.
Hg1-xCdxTe(MCT) samples epitaxial structures are irradiated by pulse electron beams under the doze 1013- 1017 cm-2. Electron beams have the next parameters: 500 eV energy electron ; 200 keV energy electron. Electroconductivity and recombination of modified samples are investigated by Hall effect and photoconductivity methods. For 200 keV electron energy beam irradiation of the n-type surface regions have been obtained under threshold mechanisms of donor defect generation.FOr 500 keV electron energy beam irradiation the maximum value of charge carrier lifetimes occur in p- to n-type conductivity conversion range for the initial p-type crystals due to the conductivity compensation. MCT samples are implanted by Al ions under the dose 1012-1016 cm-2. Ion beams have the next parameters: (1-10) A/cm2 ion current density; (100-200) ns current pulse; (150-450) keV Al ion. The ion distribution and doping profiles were investigated by PIGE and Hall effect methods. The comparison between MCT samples after power pulse ion implantation and after standard ion implantation demonstrate a difference in ion distribution, doping profiles and defect formation radiation mechanisms.
We inform on results C-V measurements of structures metal- insulator MnHgTe, in which interface insulator-MnHgTe is created anodic oxidation. Results of researchers of a structure of distribution of elements of a matrix on interface by a method Rutherford backscattering spectrometry are submitted. Interrelation between the characteristics of interface and C-V characteristics is shown. MIS-structures on MMT as with anodic oxide and with oxinitrid silicon deposition after removal anodic oxide. A nature of defects of a transient layer between oxide and MMT is discussed which requires further research. Passivation MMT by deposition SixOyNz allows to reach rather low concentration surface charge, that on the order is lower, than with anodic oxide.
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