scholarly journals Band Structure and Surface Localized States of Fe Thin Film on Cu Surface

Shinku ◽  
2004 ◽  
Vol 47 (3) ◽  
pp. 232-234 ◽  
Author(s):  
Tomoya KISHI ◽  
Hideaki KASAI ◽  
Hiroshi NAKANISHI ◽  
Wilson Agerico DIÑO ◽  
Fumio KOMORI
1972 ◽  
Vol 33 (C3) ◽  
pp. C3-21-C3-25 ◽  
Author(s):  
F. BASSANI

2018 ◽  
Vol 32 (09) ◽  
pp. 1850076 ◽  
Author(s):  
Irfan Ullah ◽  
Shaukat Ali Khattak ◽  
Tanveer Ahmad ◽  
Saman ◽  
Nayab Ali Ludhi

The titanium dioxide (TiO2) is synthesized by sol–gel method using titanium-tetra-iso-propoxide (TTIP) as a starting material, and deposited on the pre-cleaned glass substrate using spin coating technique at optimized parameters. Energy dispersive X-ray (EDX) spectroscopy confirms successful TiO2 growth. The optical properties concerning the transmission and absorption spectra show 85% transparency and 3.28 eV wide optical band gap for indirect transition, calculated from absorbance. The exponential behavior of absorption edge is observed and attributed to the localized states electronic transitions, curtailed in the indirect band gap of the thin film. The film reveals decreasing refractive index with increasing wavelength. The photoluminescence (PL) study ascertains that luminescent properties are due to the surface defects.


2017 ◽  
Vol 31 (19-21) ◽  
pp. 1740020
Author(s):  
Yuan Liu ◽  
Yun-Fei En ◽  
Wen-Xiao Fang

Low frequency noises in the p-type polycrystalline silicon thin film transistors are investigated. It shows a pure 1/f[Formula: see text] (with [Formula: see text] near one) noise behavior which can be explained by emission and trapping processes of carriers between trapping states. Subsequently, the gate voltage-dependent drain current noise power spectral densities closely follow the mobility fluctuation model, and the average Hooge’s parameter is then extracted. By considering traditional tunneling processes, the flat-band voltage spectral density is extracted and the concentration of traps in the grain boundary is calculated to be [Formula: see text]. By converting the frequency to tunneling depth of carriers in the gate oxide, the spatial distribution of gate oxide trapped charges are obtained. Finally, the distribution of localized states in the energy band is extracted. The experimental results show an exponential deep states and tail states distribution in the band gap while [Formula: see text] is about [Formula: see text], [Formula: see text] is [Formula: see text][Formula: see text]617 K, [Formula: see text] is [Formula: see text] and [Formula: see text] is [Formula: see text][Formula: see text]265 K.


2017 ◽  
Vol 31 (19-21) ◽  
pp. 1740007
Author(s):  
Kai Liu ◽  
Yuan Liu ◽  
Yu-Rong Liu ◽  
Yun-Fei En ◽  
Bin Li

Channel mobility in the p-type polycrystalline silicon thin film transistors (poly-Si TFTs) is extracted using Hoffman method, linear region transconductance method and multi-frequency C-V method. Due to the non-negligible errors when neglecting the dependence of gate-source voltage on the effective mobility, the extracted mobility results are overestimated using linear region transconductance method and Hoffman method, especially in the lower gate-source voltage region. By considering of the distribution of localized states in the band-gap, the frequency independent capacitance due to localized charges in the sub-gap states and due to channel free electron charges in the conduction band were extracted using multi-frequency C-V method. Therefore, channel mobility was extracted accurately based on the charge transport theory. In addition, the effect of electrical field dependent mobility degradation was also considered in the higher gate-source voltage region. In the end, the extracted mobility results in the poly-Si TFTs using these three methods are compared and analyzed.


2019 ◽  
Vol 9 (23) ◽  
pp. 5150 ◽  
Author(s):  
Xiaochen Zhang ◽  
Xianzhe Liu ◽  
Kuankuan Lu ◽  
Honglong Ning ◽  
Dong Guo ◽  
...  

In this work, a thin film transistor (TFT) with Zr-doped aluminum-zinc-tin oxide (Zr-AZTO) semiconductor as active layer was investigated. The Zr-AZTO thin films were co-sputtered by ZrO2 and AZTO targets (RF-Sputter) in Ar, and annealed at 350 °C in air atmosphere. With the discharge power of AZTO increasing from 100 W to 120 W, the content of Zr element decreases from 0.63 ± 0.01 at.% to 0.34 ± 0.01 at.%, and the oxygen vacancy decreases from (19.0 ± 0.1)% to (17.3 ± 0.8)%. The results of Zr-AZTO thin film show that the main factor is the co-sputter power of ZrO2 target. With the co-sputter power of ZrO2 increasing from 15 W to 45 W, the content of Zr element increases from 0.63 ± 0.01 at.% to 2.79 ± 0.01 at.%, the content of oxygen vacancy decreases from (19.0 ± 0.1)% to (14.1 ± 0.1)%, Eg increases from 2.76 eV to 2.86 eV, and the root mean square (RMS) roughness firstly decreases from 0.402 nm to 0.387 nm and then increases to 0.490 nm. The Micro Wave Photo Conductivity Decay (μ-PCD, LTA-1620SP) was used to measure the quality of Zr-AZTO thin film and the mean peak and D value decreases from 139.3 mV to 80.9 mV and from 1.54 to 0.77 as the co-sputter power of ZrO2 increases from 15 W to 45 W, which means it has highest localized states and defects in high ZrO2 co-sputter power. The devices prepared at 15 W (ZrO2)/100 W (AZTO) co-sputter show a best performance, with a μsat of 8.0 ± 0.6 cm2/(V∙S), an Ion/Ioff of (2.01 ± 0.34) × 106, and a SS of 0.18 ± 0.03 V/dec. The device of Sample B has a 0.5 V negative shift under −20 V NBS and 9.6 V positive shift under 20 V PBS.


2020 ◽  
Vol 101 (16) ◽  
Author(s):  
Norman Haag ◽  
Daniel Lüftner ◽  
Florian Haag ◽  
Johannes Seidel ◽  
Leah L. Kelly ◽  
...  

1994 ◽  
Vol 336 ◽  
Author(s):  
T. Globus ◽  
H. C. Slade ◽  
M. Shur ◽  
M. Hack

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].


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