Dark current spectroscopy (DCS) is used to study deep level traps corresponding to the bright pixels that form the histogram “tails” of irradiated charge-coupled devices (CCD). We found four distinct traps, among which the double vacancy (V2) and the vacancy-phosphorous (VP) have the highest concentrations and generation rates. We show that DCS can be used to examine the annealing mechanisms of silicon defects to concentrations as low as 5 × 107 cm−3.

Schottky barrier height (ÖB) engineering of NiGe/n-Ge(001) diodes was achieved through germanidation induced dopant segregation on As implanted-Ge substrates.was reduced from 0.55 eV to 0.16 eV with increasing As dose on n-Ge(001) while on p-Ge(001), the diodes exhibited increasing ÖB.

B12As2 epitaxial layers grown on (0001) 6H-SiC and (1120) 6H-SiC substrates have been studied using scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and synchrotron white beam x-ray topography (SWBXT) and investigated with the aid of crystal visualization software. SWBXT showed that B12As2 adopted [111] growth orientation, parallel to [0001]SiC, on c-plane 6H-SiC and adopted [101] growth orientation, parallel to [1120]SiC, on a-plane 6H-SiC. However, SWBXT also revealed the twins in both sets of the B12As2 films, consistent with the SEM observation of the surface morphology. Cross-sectional HRTEM also confirmed the presence of twins in both cases and also revealed the existence of an intermediate layer between the c-plane 6H-SiC and the B12As2 film. By correlating the HRTEM observation and crystal visualization, the atomic configurations across the twin boundaries in both samples as well as those in the intermediate layer in the c-plane sample were proposed.

A series of isothermal annealing experiments have been performed in the range 790–920°C under N2 flow in order to study the deuterium out-diffusion kinetics of Mg-doped GaN grown on sapphire under deuterated ammonia. The deuterium concentration was measured by SIMS analysis before and after each annealing step. The kinetics closely follow a first-order law. The activation energy related to the deuterium out-diffusion process is 3.1 eV. In addition, deuterium effusion measurements were performed measuring the molecular HD flux while the specimens were annealed in ultra high vacuum with a linear heating rate. In contrast to SIMS, this method detects the species that migrated out of the sample. Effusion peaks of the HD flux at 360 and 490°C are attributed to the fragmentation of adsorbed CHxDy complexes. The molecular HD flux starts increasing at 800°C which is the onset of the GaN decomposition and has its maximum at 920°C. This HD flux is accompanied by the desorption of H and D containing radicals and molecules desorbing above 900°C.

Au contacts were fabricated on pressurized melted grown n-type ZnO single crystal samples pre-treated with boiling organic solvent and hydrogen peroxide. Contacts fabricated without any pre-treatment and with boiling organic solvent pre-treatment were found to have ohmic behavior.For the samples pre-treated with hydrogen peroxide, the Au contacts were found to have rectifying property.Systematic investigation was performed to study the dependence of the Schottky barrier height and the reverse bias leakage current on the temperature and the duration of the pre-treatment.Positron annihilation spectroscopy (PAS), X-ray photoemission (XPS) and scanning electron microscope (SEM) were also used to understand how the vacancy type defect, contamination and surface morphology would influence the electrical property of the fabricated contacts.

Microwave heating is used to initiate the ion-cut process for transfer of coherent silicon-layers onto insulator substrates.Hydrogen and boron co-implanted silicon was bonded to an insulative substrate before processing inside a 2.45 GHz, 1300 W cavity applicator microwave system. Sample temperatures measured using a pyrometer were comparable to previous ion – cut studies.Selected samples were further annealed to repair any damage created in the ion implant process.Rutherford backscattering spectrometry and selective area electron diffraction patterns show high crystallinity in transferred layers.RUMP simulation of backscattering spectra and cross-sectional transmission electron microscopy demonstrate that thicknesses of the transferred layers are comparable to previous ion-cut exfoliation techniques.Surface quality as characterized by an atomic force microscope compares well with previous ion-cut studies.Hall measurements were used to characterize electrical properties of transferred layers. The mobility and carrier density of microwave activated ion – cut silicon on insulator processed samples compares well with previous annealing techniques.

Thermally grown SiO2 was implanted at room temperature with 220 keV Kr in order to generate bubbles/cavities in the sample. The formation and thermal stability of these bubbles/cavities is studied in this work. Transmission Electron Microscopy (TEM), Rutherford Backscattering Spectrometry (RBS) and Positron Annihilation Spectroscopy (PAS) were used to provide a comprehensive characterisation of defects (bubbles, vacancy, Kr and other types of defects) created by Kr implantation in SiO2 layer. These measurements suggest that the bubbles observed with TEM were a consequence of the interaction between Kr and vacancies (V), with VnXem complexes created in the whole of implanted zone. After annealing, bubbles/cavities disappear from SiO2 due to the strongly desorption of Kr and the decrease in vacancy concentration.

GaAsSb (N) superattices (SLs) grown on InP substrates using metalorganic vapor phase epitaxy are investigated by high resolution X-ray diffraction (XRD), low temperature photoluminescence (PL), and high resolution transmission electron microscopy (TEM). XRD shows very sharp satellite peaks and pendellosung fringes, which indicates excellent crystalline quality and abrupt interfaces in the GaAsSb (N)/InP SL, with Sb varies with 0.2 to 0.7.Low temperature PL shows clearly different features between the 25% Sb and 44% Sb samples.A band alignment difference is proposed to explain these behaviors. Experimental data establishes that the transition from a type-I to a type-II heterostructure occurs for a Sb-content of approximately 40%, which agrees well with the prediction by Model Solid Theory. While N incorporation degrades the PL intensity, it also provides the greater electron confinement needed to achieve mid-IR emission from GaAsSbN/GaAsSb type-II QWs

Nowadays much attention is given to the ultrasound influence on electrophysical properties and defective structure of semiconductors and semiconductor structures [1,2]. In particular, a big interest is caused by the processes which take place in the material under non-equilibrium conditions, caused by the acoustic vibration [2]. This paper is devoted to the study of the ultrasonic waves dynamic influence (in situ) on the processes of the charge transport in a silicon solar sell.

The silicon structures with p-n-transition received by phosphorus ions implantation in a surface layer of Si:B plate have been chosen as the research objects. Transition is located at 0,5 microns depth from surface, n-layer electron concentration is 1019 cm−3, hole concentration is 1.3×1015 cm−3. The specified structures I-V characteristics are measured under ultrasonic fluctuations excitation conditions. The researches were carried out both without external illumination as well as under external illumination. In the latter case, additional carriers photogeneration occurred both at the p-n-transition region and at the p-area depth. Longitudinal acoustic waves were excited in structures with help of LiNbO3 transducer; the ultrasound frequency is 4.1 and 13.6 MHz; the acoustic power is up to 3 W/cm2.

It is revealed, that the changes of diffusion parameters take place at the non-equilibrium conditions caused by ultrasonic lading. These changes are shown in photocurrent rising. Photocurrent increase reached up to 15 %, which corresponds to 2 times diffusion length increasing approximately. Also the essential (up to 40 %) acoustostimulated decreasing of the p-n-transition saturation current is revealed. The characteristic time of the observable effects is level with tens minutes. It is established, that dependence of the dynamic changes on ultrasound power is nonlinear. It is shown, that efficiency of an acoustostimulated influences raises with an ultrasound frequency.

The analysis has shown that observable effects are connected with non-equilibrium processes of defects ionization and reorientation at an acoustic field. It specifies an opportunity of a dynamic management of a charge carriers distribution processes in semiconductor structures by ultrasonic waves.

Intrinsic biaxial strain values of strained Si on insulator (SSOI) layers were measured using symmetric Bragg-Brentano configuration (i.e., {004} θ-2θ scans) and asymmetric {224} rocking curves. We confirmed that the twist angle between the layer and substrate can be incorporated into the biaxial strain equations for epitaxial layers. Moreover, as the samples were annealed up to 1200°C, the tensile parallel strains increased from 0.56% to 0.7%. Since both the overlying strained Si and underlying substrate maintained a stressed state in the buried SiO2, the compressively strained oxide retained the lattice expansion of the overlying strained Si and resulted in the increasing parallel strains after annealing.

A theoretical modeling and comparative analysis of the process of diffusion of the interstitial oxygen atoms and interstitial hydrogen molecules (H2) in silicon and germanium crystals at normal and hydrostatic pressure (HP) have beenperformed. The process of diffusion of particle with a strong interaction with a crystal lattice (interstitial oxygen atom) is a cooperative process. Three nearest Si (Ge) atoms of crystal lattice are involved in an elementary oxygen jump from a bond-center site to another bond-center site along a path in the (110) plane. It is precisely their optimum position (corresponding to a local minimum of the crystal total energy) determines the value of the diffusion parameters of an interstitial oxygen atom in silicon and germanium crystals. In a sense, the diffusion process may be considered as a diffusion process of qwasiparticle – (Oi+3Si). In the case of a particle weakly interacting with a crystal lattice (interstitial hydrogen molecules) we come up against the opposite case – the diffusion of H2 is not a cooperative process. The calculated values of the activation energy and pre-exponential factor for an interstitial oxygen atom δE(Si) = 2.59 eV, δE(Ge) = 2.05 eV,D0 (Si)= 0.28 cm2 s−1, D0 (Ge)= 0.39 cm2 s−1 and interstitial hydrogen molecule δE(Si) = 0.79 – 0.83 eV, δE(Ge) = 0.58 – 0.62 eV D0 (Si)= 7.4 10−4 cm2 s−1, D0 (Ge)= 6.510−4 cm2 s−1 are in an excellent agreement with experimental ones and for the first time describe perfectly an experimental temperature dependence of an interstitial oxygen atom and hydrogen molecules diffusion constant in Si crystals.

We report that arsenic diffusion can be enhanced and retarded by surrounding interstitial rich and vacancy rich environments created by Si point defect engineering implant. The enhancement and retardation can be attributed to the dominant arsenic interstitial diffusion mechanism during post-implant anneal. Kinetic Monte Carlo simulations with newly implemented models show good match with experiments. Our study suggests the importance of arsenic interstitial mechanism and a possible approach for n-type ultra shallow junction fabrication.

Ab initio electronic structure calculations within density functional theory have been carried out in pure GaSe and GaSe doped with substitutional impurities (Cd, In and Sn) at the Ga site in order to understand the nature of the defect states and how they depend on the nominal valence of these three impurities. We find that Cd impurity introduces a defect state located between 0.1 – 0.18 eV above the valence band, in good agreement with photoluminescence peaks seen at 0.13 eV and 0.18 eV. Using both experimental and theoretical effective mass parameters we show that effective mass model fails to describe these acceptor states. Sn changes the single particle density of states (DOS) near the bottom of the conduction band, and gives rise to resonant states deep in the valence band. In, on the other hand, behaves like Ga, it does not make noticeable change in the DOS of the host GaSe crystal.

The capability of hydrogen to passivate nitrogen in dilute nitrides is exploited to in-plane engineer the electronic properties of Ga(AsN)/GaAs heterostructures. Two methods are presented: i) by deposition of hydrogen-opaque metallic masks on Ga(AsN) and subsequent hydrogen irradiation, we artificially create zones of the crystal having the band gap of untreated Ga(AsN) surrounded by GaAs-like barriers; ii) by employing an intense (∼100 nA) and narrow (∼100 nm) beam of electrons, we dissociate the complexes formed by N and H in a spatially delimited part of a hydrogenated Ga(AsN) sample. As a consequence, in the spatial regions irradiated by the electron beam, hydrogenated Ga(AsN) recovers the smaller energy gap it had before hydrogen implantation.

GaInNAsSb quantum wells with GaNAs barriers, grown via molecular beam epitaxy (MBE) on 100–oriented GaAs substrates at varying temperatures, were analyzed using photoluminescence (PL), high-resolution x-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive spectrometry (EDS). Samples grown at 420 °C, 440 °C, and 470 °C were analyzed, as were two pieces of the 440 °C growth temperature sample that had been annealed at 740 °C and 820 °C.These measurements showed that the decrease in PL with higher growth temperatures was due to the onset of 3D growth and the nucleation of dislocations.The degradation associated with overannealing was likely due to dislocation nucleation.The poor PL associated with low growth temperatures was due to another mechanism, most likely arsenic anti-site defects.EDS measurements showed greater composition uniformity with lower growth temperatures, as expected, and also showed that there was no ordered indium-rich or indium-poor phase separation at any temperature.Phase separation upon annealing was not observed.

We report the observation of threading dislocation de-multiplication process by transmission electron microscopy (TEM). The GaN films used in this study were grown on (0001) sapphire substrates with LT-GaN buffer layers by reduced pressure organometallic vapor phase epitaxy. By using g · Db = 0 invisibility criterion, it was found that some of TDs were de-multiplicated by interactions among themselves. In particular, type a+c TDs were found to nucleate through the interactions between type a and type c TDs in GaN near the GaN/sapphire interface so that the de-multiplication of TDs in GaN films was achieved.

Four boron-implanted p-n junction silicon light-emitting diode structures were designed and simulated under an identical process flow by using Silvaco simulators.In the simulation, only boron-implant parameters and post-implant anneal conditions were varied to identify and compare the physical, electrical, and optical properties of the structures.It was found that a pillar structure with a wrapped p-n junction has the greatest radiative recombination rate. Regardless the structure type, the maximum radiative recombination rate always occurs within the p+ region. There exists a peak in the maximum radiative recombination rate when the anneal temperature increases from 700 to 1100 °C, and the anneal temperature at peak increases while the implant dose increases. Furthermore, the radiative recombination rate always increases with the implant dose but it saturates at a high dose. However, the radiative recombination rate does not change significantly with the implant energy.

The effect of excess of carbon in a-Si1−xCx:H has been studied with regard to local structure reconstruction, evolution of paramagnetic defects and photoluminescence (PL) after vacuum annealing over the temperature range 300–850°C. Two series of samples with stoichiometric (Si0.5C0.5) and carbon-rich (Si0.3C0.7) compositions were studied by Electron Paramagnetic Resonance (EPR), Photoluminescence (PL) and Raman scattering. It is found that there exist two effects responsible for the PL efficiency of a-Si1-xCx:H films: “killing” effect of carbon-related paramagnetic defects and “enhancing” effect of carbon-hydrogen bonds in Si:C-Hn configuration. A microstructure model is proposed for explaining the non-monotonic behavior of integrated PL intensity and concentration of paramagnetic centers and Si:C-Hn bonds as a function of annealing temperature. This model evolves from the following principal processes during thermal treatment of a-Si1−xCx:H: thermally activated release of weakly bonded hydrogen, migration of hydrogen within material and interaction of hydrogen with carbon-related defects.

A computational intelligence algorithm has been applied to extracting trap parameters from the photocurrent relaxation waveforms recorded at the temperature range of 20-320 K for semi-insulating (SI) InP samples. Using the inverse Laplace transform procedure, the spectral surfaces, visualized in the three dimensional space as functions of temperature and emission rate, are calculated. The processes of thermal emission of charge carriers from defect centers manifest themselves as the sharp folds on the spectral surface. Using a set of Gaussian functions, the approximating surface is created and the ridgelines of the folds, giving the temperature dependences of the emission rate for the detected traps, are determined. The approximation is performed using the support vector machine (SVM) algorithm which allows for trading off between the model complexity and fitting accuracy. The new approach is exemplified by comparing the defect structure of SI InP wafers after annealing in iron phosphide and pure phosphorous atmospheres.

Indium nitride (InN) is a promising yet technologically challenging material with a high defect density and unusual material properties. Its high electron mobility may be utilized in high power electronic devices, and its high absorbance and low energy optical response make it a promising candidate for multi-junction, high-efficient solar cell technology. Studies of absorption and photoluminescence optical response of epitaxial InN resulted in a large correction of the fundamental bandgap from the originally proposed 1.9 eV to now below 0.7 eV. Yet, it is still debated if the commonly measured optical transitions below the original high bandgap values are actually caused by a large concentration of defects, on the order of 1020/cm3, rather than reflecting a low fundamental bandgap. Many applications of this material, e.g. in high-efficient solar cell technology, are primarily dependent on the successful production of a contacted p-n junction, which has not yet been achieved. This contribution addresses the controversy in the bandgap discussion of InN. Valence electron energy loss spectroscopy (VEELS) of InN allows spatially resolved analysis of the density of states in the transmission electron microscope (TEM). Standard optical characterization is compared with results from TEM characterization.