The limiting energy resolution of SiC detectors in ion spectrometry

The Monte Carlo method is used to simulate the complete stopping of α particles in SiC. A histogram of energy losses in nuclear-scattering events is obtained. The energy-loss spectrum has the characteristic asymmetric shape with the line full width at the half-maximum FWHM_nucl ≈ 4.22 keV. The final shape of the spectral line is obtained by a convolution with the Gaussian function that describes the contribution of the ionization and noise fluctuations (originated in the detector and instrumentation) to the signal. The resulting value of FWHM for the line is equal to 8.75 keV (at a noise variance of 1.7 keV). The experimental energy resolution of the detectors was found to be poorer than the calculated value by a factor of 2. It is established that the losses of charge during its transport in the detector bulk are insignificant, so that the discrepancy between the calculated and experimental values of the resolution should be attributed to the nonoptimal design of the detector window.     

Silicon carbide transistor structures as detectors of weakly ionizing radiation

SiC-based nuclear radiation detectors figured prominently in the very first attempts of the 1960s to replace gas in ionization chambers with a more condensed semiconducting medium. However, the dynamics of improvement of SiC in those years was markedly inferior to the progress made in the development of competing materials. This study continues with the investigation of triode detector structures based on “pure” SiC films. It is established that for weakly ionizing radiation (as also in the case of strongly ionizing alpha particles) the sig-nal is amplified by no less than a factor of several tens. This allows SiC films with a thickness of about 10 µm to be used to detect penetrating radiation, e.g., X-rays, since the effective thickness of the films is on the order of hundreds of micrometers.     

Radiation hardness of wide-gap semiconductors (using the example of silicon carbide)

Results obtained in studying the effect of ionizing radiation on epitaxial layers and devices based on silicon carbide (SiC) are considered. It is shown that, in investigations of wide-gap semiconductors (WGS), account should be taken of how the rate of removal of mobile charge carriers—the standard parameter in determining the radiation hardness of a material—depends on temperature. The use of data obtained only at room temperature may lead to an incorrect assessment of the radiation hardness of WGS. A conclusion is made that the WGS properties combine, on the one hand, high radiation hardness of high-temperature devices based on these semiconductors and, on the other, the possibility of effective radiation-induced doping (e.g., for obtaining semi-insulating local regions in a material at room temperature).     

Fluorescent SiC and its application to white light-emitting diodes

Fluorescent-SiC(f-SiC),which contains donor and acceptor impurities with optimum concentrations, has high conversion efficiency from NUV to visible light caused by donor-acceptor-pair(DAP) recombination. This material can be used as a substrate for a near UV light-emitting diode(LED) stack,and leads to monolithic white LED device with suitable spectral property for general lighting applications.In this paper,we describe basic technologies of the white LED,such as optical properties of f-SiC substrate,and epitaxial growth of NUV stack on the f-SiC substrate.     

Interaction of Pb and Sn with Thin Films of Their Oxides on Single-Crystal Silicon

Experimental data are presented on the interactions between Pb and thin SnO and SnO₂ films and between Sn and thin PbO films during vacuum annealing and subsequent heat treatment in flowing oxygen. The Pb and Sn films were deposited by magnetron sputtering onto single-crystal Si substrates; the SnO and SnO₂ films were produced by heat-treating Sn in flowing oxygen at 470 and 870 K, respectively; and the PbO films were obtained by heat-treating Pb films at 520 K. During annealing of Pb/SnO₂/Si heterostructures at 870 K in a vacuum of 0.33 × 10^–2 Pa, Pb reacts with lead oxides to form PbSnO₃, whereas vacuum annealing of Sn/PbO/Si heterostructures leads to the formation of SnO and Pb metal. The lead stannates forming in vacuum persist during subsequent heat treatment in flowing oxygen at atmospheric pressure at temperatures of up to 1120 K.     

Indium Nitride at the 2D Limit

The properties of 2D InN are predicted to substantially differ from the bulk crystal. The predicted appealing properties relate to strong in‐ and out‐of‐plane excitons, high electron mobility, efficient strain engineering of their electronic and optical properties, and strong application potential in gas sensing. Until now, the realization of 2D InN remained elusive. In this work, the formation of 2D InN and measurements of its bandgap are reported. Bilayer InN is formed between graphene and SiC by an intercalation process in metal–organic chemical vapor deposition (MOCVD). The thickness uniformity of the intercalated structure is investigated by conductive atomic force microscopy (C‐AFM) and the structural properties by atomic resolution transmission electron microscopy (TEM). The coverage of the SiC surface is very high, above 90%, and a major part of the intercalated structure is represented by two sub‐layers of indium (In) bonded to nitrogen (N). Scanning tunneling spectroscopy (STS) measurements give a bandgap value of 2 ± 0.1 eV for the 2D InN. The stabilization of 2D InN with a pragmatic wide bandgap and high lateral uniformity of intercalation is demonstrated.     

Mathematical Models of Overaging Disordering of Aluminum Alloys and Their Applications

Metal Science and Heat Treatment -     

Structural defects and deep-level centers in 4H-SiC epilayers grown by sublimational epitaxy in vacuum

The parameters of deep-level centers in lightly doped 4H-SiC epilayers grown by sublimational epitaxy and CVD were investigated. Two deep-level centers with activation energies E _c -0.18 eV and E _c -0.65 eV (Z1 center) were observed and tentatively identified with structural defects of the SiC crystal lattice. The Z1 center concentration is shown to fall with decreasing uncompensated donor concentration N _d -N _a in the layers. For the same N _d -N _a , the Z1 center concentration is lower in layers with a higher dislocation density.