scholarly journals Применение метода матрицы рассеяния для расчета примесных состояний в полупроводниковых структурах

2021 ◽  
Vol 47 (7) ◽  
pp. 26
Author(s):  
С.В. Морозов ◽  
М.С. Жолудев
Keyword(s):  
Spherical Symmetry ◽  
Matrix Method ◽  
Energy Levels ◽  
Defect States ◽  
Impurity Defect ◽  
S Matrix ◽  
Luttinger Hamiltonian

We adapted S-matrix method for calculation of energy levels and carrier wavefunctions near impurity/defect states. We demonstrate the possibility of implying this method for multiband models on the example of Luttinger Hamiltonian with Coulomb acceptor in the spherical symmetry approximation. The obtained energies of discrete levels are in well agreement with results of calculations performed by other methods.

Formation process of interface states at grain boundaries in sputtered polycrystalline Si films

1999 ◽  
Vol 14 (2) ◽  
pp. 371-376 ◽  
Author(s):  
Yoshitaka Nakano ◽  
Jiro Sakata ◽  
Yasunori Taga
Keyword(s):  
Energy Levels ◽  
Columnar Structure ◽  
Systematic Investigation ◽  
Defect States ◽  
Electron Microscopic ◽  
Thermally Induced ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Si Films ◽  
Induced Changes

A systematic investigation has been made on surface defect states of crystallites in the crystallization process of sputtered amorphous silicon films by isothermal annealing. Transmission electron microscopic observations indicate a pronounced vertical columnar structure in the upper part of the films, where the crystallization is delayed. Admittance spectroscopy reveals that two newly generated energy levels with the crystallization are attributed to the crystallites in the lower and upper parts of the films in view of the anisotropic crystallization. These thermally induced changes can be well explained by Si–Si shearing modes at the interfaces of crystallites through the process of crystallization.

Deep Level Defect Studies in Mocvd-Grown InxGa1−sAs1−yNy Films Lattice-Matched to GaAs

1998 ◽  
Vol 535 ◽  
Author(s):  
Daewon Kwon ◽  
R. J. Kaplar ◽  
J. J. Boeckl ◽  
S. A. Ringel ◽  
A. A. Allerman ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Deep Level ◽  
Energy Levels ◽  
Resolution Limit ◽  
Defect States ◽  
Cross Sectional ◽  
Order Of Magnitude ◽  
Transient Spectroscopy ◽  
Lattice Matched ◽  
Dlts Spectra

AbstractDeep level defects in MOCVD-grown, unintentionally doped p-type InGaAsN films lattice matched to GaAs were investigated using deep level transient spectroscopy (DLTS) measurements. As-grown p-InGaAsN showed broad DLTS spectra suggesting that there exists a broad distribution of defect states within the band-gap. Moreover, the trap densities exceeded 1015 cm−3. Cross sectional transmission electron microscopy (TEM) measurements showed no evidence for threading dislocations within the TEM resolution limit of 107 cm−2. A set of samples was annealed after growth for 1800 seconds at 650 °C to investigate the thermal stability of the traps. The DLTS spectra of the annealed samples simplified considerably, revealing three distinct hole trap levels with energy levels of 0.10 eV, 0.23 eV, and 0.48 eV above the valence band edge with trap concentrations of 3.5 × 1014 cm−3, 3.8 × 1014 cm−3, and 8.2 × 1014 cm−3, respectively. Comparison of as-grown and annealed DLTS spectra showed that post-growth annealing effectively reduced the total trap concentration by an order of magnitude across the bandgap. However, the concentration of a trap with an energy level of 0.48 eV was not affected by annealing indicating a higher thermal stability for this trap as compared with the overall distribution of shallow and deep traps.

scholarly journals The S Matrix Method in Pion Reactions

1952 ◽  
Vol 8 (1) ◽  
pp. 53-76 ◽  
Author(s):  
T. Nakano ◽  
K. Nishijima
Keyword(s):  
Matrix Method ◽  
S Matrix

Energy Levels of Defects in a-Si:H From Optical and Electrical Characteristics

1996 ◽  
Vol 424 ◽  
Author(s):  
T. Globus
Keyword(s):  
Thin Films ◽  
Energy Levels ◽  
Thin Film Transistor ◽  
Close Correlation ◽  
Device Fabrication ◽  
Defect States ◽  
Optical Interference ◽  
Hydrogenated Silicon ◽  
Transfer Characteristics ◽  
Wide Range

AbstractTwo novel characterization techniques for hydrogenated silicon thin films have been recently proposed which show promise in providing critical feedback for evaluating materials and monitoring the device fabrication process. The first technique is the optical interference spectroscopy for a quick non-destructive measurement of absorption coefficient and refractive index spectra of amorphous- and poly-Si thin films in a wide range of the incident photon energies (0.5–3.5 eV) [1]. By using this technique, the absorption related to defects in the subgap energy region has been determined for device quality thin films. The second technique is the novel version of the field effect conductivity (FEC) method for the direct density-of-states (DOS) determination from analysis of thin film transistor (TFT) quasi-static transfer characteristics [2]. This sensitive, fast, and easy to use, method makes it possible to resolve fine-scale features in the midgap DOS of a-Si:H. In this work, data from two methods of spectroscopy are analyzed together. Very close correlation of results is demonstrated which provides a unique opportunity to identify midgap defect states and to understand the fundamental physics of hydrogenated silicon films. The energy map of defect states in the upper half of a-Si:H bandgap is presented. These results permits to use TFT transfer characteristics and optical interference technique measurements as effective tools to control the quality of TFF manufacturing process.

scholarly journals Unravelling the impact of Ta doping on the electronic and structural properties of titania: A combined theoretical and experimental approach

2021 ◽  
Author(s):  
Vignesh Kumaravel ◽  
Maria Barbara Maccioni ◽  
Snehamol Mathew ◽  
Steven Hinder ◽  
John Bartlett ◽  
...  
Keyword(s):  
Crystal Lattice ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Structural Characteristics ◽  
Energy Levels ◽  
Average Crystallite Size ◽  
Defect States ◽  
X Ray ◽  
The Impact ◽  
Ta Doping

The introduction of new energy levels in the forbidden band through the doping of metal ions is an effective strategy to improve the thermal stability of TiO2. In the present study, the impact of Ta doping on the anatase to rutile transition (ART), structural characteristics, anion and cation vacancy formation were investigated in detail using Density Functional Theory (DFT) and experimental characterisation including, X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS). The average crystallite size of TiO2 decreases with an increase in the Ta concentration. At high temperatures, more oxygen atoms entered the crystal lattice and occupy the vacancies, leading to lattice expansion. Importantly, we find that Ta doping preserved the anatase content of TiO2 up to annealing temperatures of 850 °C which allows anatase stability to be maintained at typical ceramic processing temperatures. The substitution of Ti4+ by the Ta5+ ions increased the electron concentration in the crystal lattice through formation of Ti3+ defect states. Raman studies revealed the formation of new Ta bonds via disturbing the Ti-O-Ti bonds in the crystal lattice. It is concluded that under the oxidising conditions, Ta5+ ions could be enhanced on Ta-TiO2 surface due to the slow diffusion kinetics.

scholarly journals Особенности спектров примесной фотопроводимости эпитаксиальных пленок PbSnTe(In) при изменении температуры

2019 ◽  
Vol 53 (9) ◽  
pp. 1303
Author(s):  
А.В. Иконников ◽  
В.И. Черничкин ◽  
В.C. Дудин ◽  
Д.А. Акопян ◽  
А.Н. Акимов ◽  
...  
Keyword(s):  
Far Infrared ◽  
Epitaxial Films ◽  
Infrared Range ◽  
Fourier Spectroscopy ◽  
Interband Transitions ◽  
Defect States ◽  
Impurity Defect ◽  
Additional Illumination

AbstractThe photoconductivity spectra of PbSnTe(In) epitaxial films are investigated by Fourier spectroscopy in the far infrared range at temperatures from 4.2 to 32.4 K. In addition to interband transitions, subgap features associated with the excitation of impurity-defect states are found in the spectra. The evolution of the spectra with temperature and additional illumination is traced.

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