Comparison of Electron Beam-Induced and Light-Induced Defect Saturation in a-Si:H

1992 ◽  
Vol 258 ◽  
Author(s):  
M. Grimbergen ◽  
A. Lopez-Otero ◽  
A. Fahrenbruch ◽  
L. Benatar ◽  
D. Redfield ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Irradiation ◽  
Defect Density ◽  
Dark Conductivity ◽  
High Light Intensity ◽  
Generation Rate ◽  
Temperature Dependent ◽  
Photon Irradiation ◽  
Temperature Ranges ◽  
Induced Defects

ABSTRACTGeneration, saturation, and annealing characteristics of metastable defects formed by electron beam irradiation at 20 keV and photon irradiation at 1.9 eV have been compared. Saturation density reached by electron irradiation is temperature independent over the range 225 K to 300 K, although a small activation energy of the generation rate may be present. This differs from observed temperature dependent light-induced saturation from 330 K to 470 K, although differences are expected because of the separate temperature ranges and dissimilar carrier excitation rates. The electron beam-induced saturated defect density is about 5 times larger than for light-induced saturation at 350 K and high light intensity (generation rate ≈ 1022cm-3s-1). Defects formed by electron irradiation anneal at 300 K with a stretched exponential time constant three orders of magnitude smaller than for light-induced defects. After electron irradiation, dark conductivity relaxes faster than photoconductivity. Once the dark Fermi level becomes constant during defect density relaxation, photoconductivity is inversely proportional to the defect density.

Relaxation of Electron Beam-Induced Metastable Defects in a-Si:II

1993 ◽  
Vol 297 ◽  
Author(s):  
M. Grimbergen ◽  
R. Mcconville ◽  
D. Redfield ◽  
R.H. Bube
Keyword(s):  
Activation Energy ◽  
Electron Beam ◽  
Amorphous Silicon ◽  
Time Constant ◽  
Electron Irradiation ◽  
Defect Density ◽  
Initial Density ◽  
Induced Defects ◽  
Metastable Defect

Relaxation of the metastable defect density in undoped amorphous silicon is observed after keV electron irradiation. The time constant for relaxation has an activation energy close to 1 eV, similar to that for light-induced defects. Relaxation appears to follow two or more stages. A large initial density relaxes rapidly, followed by slower relaxation more characteristic of light-induced defects. Separation of these components allows for a better comparison of e-beam and light-induced saturation defect density.

An Alternative Model for the Kinetics of Light-Induced Defects in A-Si:H

1991 ◽  
Vol 219 ◽  
Author(s):  
Paulo V. Santos ◽  
W. B. Jackson ◽  
R. A. Street
Keyword(s):  
Time Dependence ◽  
Valence Band ◽  
Defect Formation ◽  
Defect Density ◽  
Generation Rate ◽  
Band Tail ◽  
Defect Generation ◽  
Wide Range ◽  
Induced Defects ◽  
Kinetics Of

ABSTRACTThe kinetics of light-induced defect generation in a-Si:H was investigated over a wide range of illumination intensities and temperatures. The defect density around 1016cm-3 exhibits a power-law time dependence Ns ∼ G2εfε with ε = 0.2 to 0.3, where G is the photo-carrier generation rate. A model for the kinetics of defect generation is proposed based on the existence of an exponential distribution of defect formation energies in the amorphous network, associated with the valence band tail states. The model reproduces the observed time dependence of the defect density with an exponent e determined by the exponential width of the valence band tail. The temperature dependence of the defect generation rate is well-reproduced by the model, which provides a connection between the Stabler-Wronski effect and the weak-bond model.

Defect Saturation in a-SiGe:H(F) Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
N.W. Wang ◽  
P.A. Morin ◽  
V. Chu ◽  
S. Wagner
Keyword(s):  
Steady State ◽  
Low Temperature ◽  
Light Intensity ◽  
Carrier Concentration ◽  
Thermal Annealing ◽  
Defect Density ◽  
High Light Intensity ◽  
High Light ◽  
The Other ◽  
Induced Defects

ABSTRACTIt is a question as yet unresolved whether the density of light-induced defects in a-Si:H reaches a saturated value that cannot fundamentally be exceeded, or whether the defect density is in all conditions a steady-state value that reflects carrier concentration and temperature. In our experiments on a-Si:H we have observed defect saturation at low temperature and high light intensity; on the other hand, data exhibiting no saturation have also been published. To learn more about this question we have carried out saturation experiments on a-SiGe:H(F) alloys. These alloys have lower defect freeze-in temperatures than a-Si:H and, presumably, lower annealing energies. Therefore, saturation should be more difficult to achieve in the alloys than in a-Si:H.We have studied saturation for a-SiGe:H(F) samples to temperatures above the onset of thermal annealing and have observed that its behavior is similar to that seen in a-Si:H.

scholarly journals Structural Modifications of Multi-walled Carbon Nanotubes of Different Diameters through Electron Beam Irradiation

1970 ◽  
Vol 46 (1) ◽  
pp. 9-16 ◽  
Author(s):  
AKM Fazle Kibria
Keyword(s):  
Carbon Nanotubes ◽  
Electron Beam ◽  
Electron Irradiation ◽  
Structural Modifications ◽  
Multi Walled Carbon Nanotubes ◽  
Graphitic Shell ◽  
Different Diameters ◽  
Walled Carbon Nanotubes ◽  
Induced Defects ◽  
Irradiation Induced Defects

The effects of irradiation on the structure of purified multi-walled carbon nanotubes (MWCNTs) having 6-19 graphitic shells and outer diameters of 8.15-17.11 nm were investigated using electron beam of energies 200 keV and dose of 2.16 x 1017 e cm-2s-1. It was observed that the electron irradiation created a number of chronological alterations in the tube structures. These were identified to be tube contraction, destruction of the innermost graphitic shell, deformation of graphitic shells and its proliferation, break down of the graphitic shells and their spreading into the tube hole and finally the destruction of the whole tube. MWCNTs having the largest innermost diameter found suffer from the highest contraction. The tube contraction behavior found stops when the innermost graphitic shell starts to destroy. Irradiation affected the innermost graphitic shell first and that of the smallest diameter was the more rapidly. It occurred probably due to having the highest curvature value. Tubes having inner shell of diameter about 4.8 nm suffer from fractional destruction within 5-15 s of irradiation exposure. Such a shell was ruined within 1 minute of irradiation exposure but that of diameter 7.0 nm was survived up to 2 minutes. It seems that the irradiation induced defects created in the MWCNTs can be used for the diversified applications of nanotubes such as the hydrogen storage enhancement in them. Keywords: Carbon nanotube; Electron irradiation; Tube contraction; Innermost shell; Defect. DOI: http://dx.doi.org/10.3329/bjsir.v46i1.8099 Bangladesh J. Sci. Ind. Res. 46(1), 9-16, 2011  

Study of electron beam irradiation induced defectivity in mono and bi layer graphene and the influence on Raman band position and line-width

2009 ◽  
Vol 1184 ◽  
Author(s):  
Gayathri Rao ◽  
Sarah Mactaggart ◽  
Ji Ung Lee ◽  
Robert Geer
Keyword(s):  
Raman Spectroscopy ◽  
Electron Beam ◽  
Line Width ◽  
Defect Density ◽  
Raman Band ◽  
Layer Graphene ◽  
Stacking Order ◽  
Nanoscale Metrology ◽  
Beam Dose ◽  
Induced Defects

AbstractNanoscale metrology of graphene-based devices is a substantial challenge. The investigation of defects and stacking order is essential for graphene-based device development. Raman spectroscopy is a useful approach in this regard. The defect-induced Raman D band yields substantial insights regarding defect density and, consequently, can serve as in important tool to quantify impact of defects on eventual graphene-based device performance. Toward this end an investigation of electron beam-induced defects in bi-layer and mono layer graphene samples has been undertaken via the examination of the Raman D, and G bands. The evolution of the aforementioned Raman spectra as a function of electron beam dose was characterized via Raman spectroscopy and compared with spectra from the same samples prior to irradiation. Defect generation in the graphene as a function of electron beam dose was characterized via the change in the intensity ratios of the Raman D and G bands (ID/IG) and the broadening of the G band line width. Continued irradiation at very high flux and very low accelerating voltages have also revealed charge accumulation evident from the narrowing of G band line-widths.

Temperature‐dependent Formation of Ozone in Solid Oxygen by 5 keV Electron Irradiation and Implications for Solar System Ices

2007 ◽  
Vol 669 (2) ◽  
pp. 1414-1421 ◽  
Author(s):  
Bhalamurugan Sivaraman ◽  
Corey S. Jamieson ◽  
Nigel J. Mason ◽  
Ralf I. Kaiser
Keyword(s):  
Solar System ◽  
Electron Irradiation ◽  
Temperature Dependent ◽  
Solid Oxygen

scholarly journals Study and Assessment of Defect and Trap Effects on the Current Capabilities of a 4H-SiC-Based Power MOSFET

Electronics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 735
Author(s):  
Fortunato Pezzimenti ◽  
Hichem Bencherif ◽  
Giuseppe De Martino ◽  
Lakhdar Dehimi ◽  
Riccardo Carotenuto ◽  
...  
Keyword(s):  
Drain Current ◽  
Oxide Semiconductor ◽  
Temperature Dependent ◽  
Channel Mobility ◽  
Blocking Voltage ◽  
Current Voltage ◽  
Wide Range ◽  
Temperature Ranges ◽  
Joint Contribution ◽  
State Resistance

A numerical simulation study accounting for trap and defect effects on the current-voltage characteristics of a 4H-SiC-based power metal-oxide-semiconductor field effect transistor (MOSFET) is performed in a wide range of temperatures and bias conditions. In particular, the most penalizing native defects in the starting substrate (i.e., EH6/7 and Z1/2) as well as the fixed oxide trap concentration and the density of states (DoS) at the 4H-SiC/SiO2 interface are carefully taken into account. The temperature-dependent physics of the interface traps are considered in detail. Scattering phenomena related to the joint contribution of defects and traps shift the MOSFET threshold voltage, reduce the channel mobility, and penalize the device current capabilities. However, while the MOSFET on-state resistance (RON) tends to increase with scattering centers, the sensitivity of the drain current to the temperature decreases especially when the device is operating at a high gate voltage (VGS). Assuming the temperature ranges from 300 K to 573 K, RON is about 2.5 MΩ·µm2 for VGS > 16 V with a percentage variation ΔRON lower than 20%. The device is rated to perform a blocking voltage of 650 V.

scholarly journals Tetragonal–Cubic Phase Transition and Low-Field Dielectric Properties of CH3NH3PbI3 Crystals

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4215
Author(s):  
Roxana E. Patru ◽  
Hamidreza Khassaf ◽  
Iuliana Pasuk ◽  
Mihaela Botea ◽  
Lucian Trupina ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Current Knowledge ◽  
Cubic Phase ◽  
Relaxation Processes ◽  
Temperature Dependent ◽  
Thermally Activated ◽  
Low Field ◽  
Conduction Mechanisms ◽  
Temperature Ranges ◽  
Nyquist Plots

The frequency and temperature dependence of dielectric properties of CH3NH3PbI3 (MAPI) crystals have been studied and analyzed in connection with temperature-dependent structural studies. The obtained results bring arguments for the existence of ferroelectricity and aim to complete the current knowledge on the thermally activated conduction mechanisms, in dark equilibrium and in the presence of a small external a.c. electric field. The study correlates the frequency-dispersive dielectric spectra with the conduction mechanisms and their relaxation processes, as well as with the different transport regimes indicated by the Nyquist plots. The different energy barriers revealed by the impedance spectroscopy highlight the dominant transport mechanisms in different frequency and temperature ranges, being associated with the bulk of the grains, their boundaries, and/or the electrodes’ interfaces.

Temperature Dependent Photoluminescence of ZnSe/Alq3 Hybrid Heterostructure

2008 ◽  
Vol 55-57 ◽  
pp. 493-496
Author(s):  
Wisanu Pecharapa ◽  
P. Potirak ◽  
W. Yindeesuk
Keyword(s):  
Electron Beam ◽  
Quantum Efficiency ◽  
Exciton State ◽  
Temperature Dependent ◽  
Pl Spectra ◽  
20 Nm ◽  
Temperature Dependent Photoluminescence

II-VI inorganic/organic heterostructures consisting of ZnSe and tris(8-hydroxyquinoline) aluminum (Alq3) were prepared by electron beam evaporator. Alq3 layer with 20 nm was grown between 200-nm ZnSe layers. Photoluminescence measurement was conducted at various temperatures in order to investigate the important temperature-dependent parameters of this structure. PL spectra revealed thermal population of exciton state and the change in PL quantum efficiency of the film.

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