scholarly journals Effect of Various Parameters on Flat Region of Occupancy Function of non-Crystalline Silicon with Statistical Analysis

2019 ◽  
Vol 54 (4) ◽  
Author(s):  
Mazen M. A. Al Ibraheemi ◽  
Zainb Hassan Radhy
Keyword(s):  
Energy Gap ◽  
Crystalline Silicon ◽  
Industrial Applications ◽  
Localized States ◽  
Regression Equations ◽  
Flat Region ◽  
Simulink Model ◽  
Leading Position ◽  
Significant Addition ◽  
Occupancy Function

Non-crystalline silicon has a leading position in many fields of electronic industrial applications. With this type of silicon material, localized states in the middle of the energy gap, play an important role in determining the wafer characteristic. Therefore, the region around the middle of the energy gap is regarded as the center of charge carrier activities, whereas the occupancy function is employed to define the condition of the localized states, whether they are empty or filled with charge carriers. The occupancy function is divided into three parts within the energy gap. The most important part is the gap center which is always a flat region of a certain width and level. This paper investigates the effect of various parameters on width and level of the flat region of the silicon wafer occupancy function. The work was achieved with the aid of statistical approaches for curve fitting through regression equations. The main contribution is verified through creating a novel MATLAB-SIMULINK model for this case study. The proposed model may represent a significant addition to the Simulink library that does not have such a modelling block.

Determination of Density of Localized States in Amorphous Silicon Alloys From the Low Field Conductance of Thin N-I-N Diodes

1985 ◽  
Vol 49 ◽  
Author(s):  
Michael Shur ◽  
Michael Hack
Keyword(s):  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Bulk Density ◽  
Density Of States ◽  
Energy Gap ◽  
Localized States ◽  
New Technique ◽  
Silicon Alloys ◽  
Low Field ◽  
Density Of Localized States

AbstractWe describe a new technique to determine the bulk density of localized states in the energy gap of amorphous silicon alloys from the temperature dependence of the low field conductance of n-i-n diodes. This new technique allows us to determine the bulk density of states in the centre of a device, and is very straightforward, involving fewer assumptions than other established techniques. Varying the intrinsic layer thickness allows us to measure the,density of states within approximately 400 meV of midgap.We measured the temperature dependence of the low field conductance of an amorphous silicon alloy n-i-n diode with an intrinsic layer thjckness of 0.45 microns and deduced the density of localised states to be 3xlO16cm−3 eV−1 at approximately 0.5 eV below the bottom of the conduction band. We have also considered the high bias region (the space charge limited current regime) and proposed an interpolation formula which describes the current-voltage characteristics of these structures at all biases and agrees well with our computer simulation based on the solution of the complete system of transport equations.

Luminescent Amorphous Silicon Layers

1997 ◽  
Vol 486 ◽  
Author(s):  
G. Allan ◽  
C. Delerue ◽  
M. Lannoo
Keyword(s):  
Electronic Structure ◽  
Amorphous Silicon ◽  
Radiative Recombination ◽  
Crystalline Silicon ◽  
Tight Binding ◽  
Blue Shift ◽  
Localized States ◽  
Structure Model ◽  
Radiative Recombination Rate ◽  
Tight Binding Approximation

AbstractThe electronic structure of amorphous silicon layers has been calculated within the empirical tight binding approximation using the Wooten-Winer-Weaire atomic structure model. We predict an important blue shift due to the confinement for layer thickness below 3 nm and we compare with crystalline silicon layers. The radiative recombination rate is enhanced by the disorder and the confinement but remains quite small. The comparison of our results with experimental results shows that the density of defects and localized states in the studied samples must be quite small.

Defect states in amorphous Ge2Sb2Te5 phase change material

2014 ◽  
Vol 92 (7/8) ◽  
pp. 619-622
Author(s):  
N. Qamhieh ◽  
S.T. Mahmoud ◽  
A.I. Ayesh
Keyword(s):  
Fermi Level ◽  
Energy Gap ◽  
Continuous Distribution ◽  
Dark Conductivity ◽  
Localized States ◽  
Defect States ◽  
Thermally Activated ◽  
Level Shifts ◽  
Gap States ◽  
Change Material

Steady-state photoconductivity measurements in the temperature range 100–300 K on amorphous Ge2Sb2Te5 thin film prepared by dc sputtering are analyzed. The dark conductivity is thermally activated with a single activation energy that allocates the position of the Fermi level approximately in the middle of the energy gap relative to the valance band edge. The temperature dependence of the photoconductivity ensures the presence of a maximum normally observed in chalcogenides with low- and high-temperature slopes, which predict the location of discrete sets of localized states (recombination levels) in the gap. The presence of these defect states close to the valence and conduction band edges leaves the quasi Fermi level shifts in a continuous distribution of gap states at high temperatures, as evidenced from the γ values of the lux–ampere characteristics.

Density of Deep Bandgap States in Amorphous Silicon From the Temperature Dependence of Thin Film Transistor Current

1994 ◽  
Vol 336 ◽  
Author(s):  
T. Globus ◽  
H. C. Slade ◽  
M. Shur ◽  
M. Hack
Keyword(s):  
Thin Film ◽  
Activation Energy ◽  
Amorphous Silicon ◽  
Conduction Band ◽  
Energy Gap ◽  
Localized States ◽  
Flat Band ◽  
Gate Bias ◽  
Density Of Localized States ◽  
Wide Range

ABSTRACTWe have measured the current-voltage characteristics of amorphous silicon thin film transistors (a-Si TFTs) over a wide range of temperatures (20 to 160°C) and determined the activation energy of the channel current as a function of gate bias with emphasis on the leakage current and subthreshold regimes. We propose a new method for estimating the density of localized states (DOS) from the dependence of the derivative of activation energy with respect to gate bias. This differential technique does not require knowledge of the flat-band voltage (VFB) and does not incorporate integration over gate bias. Using this Method, we have characterized the density of localized states with energies in the range 0.15–1.2 eV from the bottom of the conduction band and have found a wide peak in the DOS in the range of 0.8–0.95 eV below the conduction band. We have also observed that the DOS peak in the lower half of the bandgap increases in magnitude and shifts towards the conduction band as a result of thermal and bias stress. We also measured an overall increase in the DOS in the upper half of the energy gap and an additional peak, centered at 0.2 eV below the conduction band, which appear due to the applied stress. These results are in qualitative agreement with the defect pool Model [1,2].

scholarly journals Hydrogenated Nano-Crystalline Silicon Thin Films in SiO2 Matrix for Next Generation Solar Cells Using Glow Discharged Decomposition

2018 ◽  
Vol 8 (1) ◽  
pp. 25
Author(s):  
Moniruzzaman Syed ◽  
Cameron Hynes ◽  
Brittany Anderson ◽  
Temer S Ahmadi ◽  
Boon Tong Goh ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Energy Gap ◽  
Volume Fraction ◽  
Crystalline Silicon ◽  
Strong Dependence ◽  
Blue Shift ◽  
Nanocrystalline Silicon ◽  
Optical Energy Gap ◽  
Substrate Temperatures

Hydrogenated Nanocrystalline Silicon (nc-Si:H) thin films using SiH4/H2 mixture by glow discharged decomposition were investigated on c-Si and glass substrates. The effects of substrate temperature on the Structural, Optical and Electrical properties of the films were investigated by X-ray diffraction, Raman scattering, FT/IR, Optical transmission and Atomic Force Microscopy (AFM). Substrate temperatures ([TSB]) of the films were changed from 100oC to 250oC. It has been revealed the strong dependence on the film’s properties with the substrate temperatures. XRD and Raman measurements were shown that the higher substrate temperature (250oC) exhibits the highest crystalline volume fraction ([ρ] = 95%) and the lowest crystalline size ([Ω] = 3.5 nm) as well, having the highest H-content and the lowest O-content. At 250oC, the lowest mobility and the highest resistivity were also found to be ~37.5 cm2/v.s and 7.35 Ω-cm. Refractive index and the optical energy gap (Eg) were estimated by 3.8 and 1.9 eV having the growth rate of 4.2 nm/min. At 250oC, it was resulted in a blue shift of the absorption edge having uniform grain distributions. Results indicate that in situ hydrogen cleaning effects is prominent and localized orderly high density Si-Si bonds are exhibiting quantum size effects at highest substrate temperature.

The Optical Spectra of a-Si:H and a-SiC:H Thin Films Measured by the Absolute Photothermal Deflection Spectroscopy (PDS)

2014 ◽  
Vol 213 ◽  
pp. 19-28 ◽  
Author(s):  
Zdenek Remes ◽  
Ravi Vasudevan ◽  
Karol Jarolimek ◽  
Arno H.M. Smets ◽  
Miro Zeman
Keyword(s):  
Thin Films ◽  
Spectral Range ◽  
Near Infrared ◽  
Energy Gap ◽  
Chemical Vapor ◽  
Visible Spectral Range ◽  
Localized States ◽  
Rf Plasma ◽  
Detection Range ◽  
The Absolute

The new absolute PDS setup allows to measure simultaneously the absolute values of the optical transmittance T, reflectance R and absorptance A spectra in the spectral range 280 2000 nm with the typical spectral resolution 10 nm in ultraviolet and visible spectral range and 20 nm in the near infrared region. The PDS setup provides the dynamic detection range in the optical absorptance up to 4 orders of magnitude using non-toxic liquid perfluorohexane Fluorinert FC72. Here we demonstrate the usability of this setup on a series of intrinsic as well as doped a-Si:H and a-SiC:H thin films deposited on glass substrates by radio frequency (RF) plasma enhanced chemical vapor deposition (CVD) from hydrogen, silane and methane under various conditions. The increase of the Tauc gap with increasing carbon concentration in intrinsic a-SiC:H was observed. The defect-induced localized states in the energy gap were observed in doped a-Si:H as well as undoped a-SiC:H below the Urbach absorption edge.

scholarly journals The configurational energy gap between amorphous and crystalline silicon

2011 ◽  
Vol 5 (10-11) ◽  
pp. 361-363 ◽  
Author(s):  
F. Kail ◽  
J. Farjas ◽  
P. Roura ◽  
C. Secouard ◽  
O. Nos ◽  
...  
Keyword(s):  
Energy Gap ◽  
Crystalline Silicon ◽  
Configurational Energy

Characteristics of Amorphous Silicon Based Alloy Field Effect Transistors

1984 ◽  
Vol 33 ◽  
Author(s):  
M. Shur ◽  
M. Hack ◽  
C. Hyun
Keyword(s):  
Amorphous Silicon ◽  
Field Effect ◽  
Energy Gap ◽  
Field Effect Transistors ◽  
Localized States ◽  
Flat Band ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
A New Technique ◽  
Silicon Based

ABSTRACTWe have developed a new theory to describe the current-voltage characteristics of amorphous silicon based alloy field effect transistors. We show that the transition from below to above threshold operation occurs when the Fermi level in the accumulation region moves from the deep to tail localized states in the energy gap and that the field effect mobility is dependent on gate voltage. We also propose a new technique to determine the flat-band voltage from the I-V characteristics in the below threshold regime.

Bias Stress Induced Instabilities in Amorphous Silicon Nitride / Crystalline Silicon and Amorphous Silicon Nitride / Amorphous Silicon Structures

1991 ◽  
Vol 219 ◽  
Author(s):  
J. Kanicki ◽  
C. Godet ◽  
A. V. Gelatos
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Crystalline Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Localized States ◽  
Negative Bias ◽  
Amorphous Silicon Nitride ◽  
Bias Stress ◽  
Silicon Structures ◽  
Hydrogenated Amorphous

ABSTRACTThe effects of positive and negative bias stress on hydrogenated amorphous silicon nitride / crystalline silicon and hydrogenated amorphous silicon nitride / hydrogenated amorphous silicon (a-Si:H) structures are investigated as a function of stress time, stress temperature and stress bias. It is shown that in both structures bias stress induces a parallel shift of the C-V (capacitance-voltage) characteristics. For a given stress bias the direction of the C-V shift depends on the sign of the applied stress voltage, while the magnitude of the C-V shift depends on stress time and temperature. In addition, it is shown that positive bias stress slightly increases the number of localized states in the a-Si:H mobility gap, but negative bias stress does not. These results lead us to conclude that the C-V shift is not induced by dangling bond defects in a-Si:H but rather by carrier trapping in the insulator.

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