Role of an interlayer at a TiN/Ge contact to alleviate the intrinsic Fermi-level pinning position toward the conduction band edge

2014 ◽  
Vol 104 (13) ◽  
pp. 132109 ◽  
Author(s):  
Keisuke Yamamoto ◽  
Masatoshi Mitsuhara ◽  
Keisuke Hiidome ◽  
Ryutaro Noguchi ◽  
Minoru Nishida ◽  
...  
Keyword(s):  
Fermi Level ◽  
Conduction Band ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Fermi Level Pinning

NEGATIVE MAGNETORESISTANCE IN PbTe(Mn,Cr)

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3343-3346 ◽  
Author(s):  
D. KHOKHLOV ◽  
I. IVANCHIK ◽  
A. KOZHANOV ◽  
A. MOROZOV ◽  
E. SLYNKO ◽  
...  
Keyword(s):  
Fermi Level ◽  
Band Edge ◽  
Negative Magnetoresistance ◽  
Conduction Band Edge ◽  
Valence Band Edge ◽  
Narrow Gap ◽  
Magnetoresistance Effect ◽  
Fermi Level Pinning ◽  
P Type ◽  
Substantial Drop

We have observed the negative magnetoresistance effect in the narrow-gap PbTe(Mn,Cr) semiconductor, in which the Fermi level is pinned within the gap nearby the conduction band edge. Previously the giant negative magentoresistance effect has been reported in PbTe(Mn,Yb), in which the Fermi level is pinned in the gap nearby the valence band edge. It is known that in the case of Yb doping the Fermi level pinning results from the 2+ - 3+ valence instability of an impurity. The same sort of the valence instability provides the Fermi level pinning in PbTe(Mn,Cr), but the conductivity is of the n-type, not of the p-type as in PbTe(Mn,Yb). Introduction of magnetic field leads to substantial drop of the PbTe(Mn,Cr) resistivity of about 30% at T = 4.2 K. This is however much lower than in PbTe(Mn,Yb), where the effect amplitude reached 3 orders of magnitude. The effect disappears at T = 15 K. Possible mechanisms of the effect are discussed.

Photoconductivity Recombination Kinetics in GaN films

2000 ◽  
Vol 622 ◽  
Author(s):  
M. Misra ◽  
T.D. Moustakas
Keyword(s):  
Molecular Beam Epitaxy ◽  
Fermi Level ◽  
Conduction Band ◽  
Molecular Beam ◽  
Excitation Intensity ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Photoconductive Gain ◽  
Photoconductive Detectors ◽  
Recombination Kinetics

ABSTRACTPhotoconductive detectors were fabricated on autodoped n-GaN films, with resistivity varying from 10 Ohm-cm to 107Ohm-cm, by molecular beam epitaxy. The mobility-lifetime product, determined from the measurement of photoconductive gain, was found to decrease monotonically from 10−2 cm2/V to 10−7 cm2/V as the dark resistivity was increased. This variation in the ντ products is attributed to changes in photocarrier lifetimes. In order to understand the recombination mechanisms responsible for this photoconductive behavior, the dependence of photoconductivity on excitation intensity (δμσ fλ) was investigated. The exponent λ was found to vary from 0.5 to 1.0, as the dark resistivity of the films increased. These results indicate the presence of exponential band tails extending from the conduction band edge. Furthermore, the dependence of photoconductivity on dark resistivity indicates that the photoconductive response is governed primarily by the location of the dark fermi level. A model accounting for these observations is presented.

scholarly journals Conduction Band Edge Energy Profile Probed by Hall Offset Voltage in InGaZnO Thin Films

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 822
Author(s):  
Hyo-Jun Joo ◽  
Dae-Hwan Kim ◽  
Hyun-Seok Cha ◽  
Sang-Hun Song
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Conduction Band ◽  
Electron System ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Offset Voltage ◽  
Three Samples ◽  
Dimensional Electron System ◽  
Longitudinal Distance

We measured and analyzed the Hall offset voltages in InGaZnO thin-film transistors. The Hall offset voltages were found to decrease monotonously as the electron densities increased. We attributed the magnitude of the offset voltage to the misalignment in the longitudinal distance between the probing points and the electron density to Fermi energy of the two-dimensional electron system, which was verified by the coincidence of the Hall voltage with the perpendicular magnetic field in the tilted magnetic field. From these results, we deduced the combined conduction band edge energy profiles from the Hall offset voltages with the electron density variations for three samples with different threshold voltages. The extracted combined conduction band edge varied by a few tens of meV over a longitudinal distance of a few tenths of µm. This result is in good agreement with the value obtained from the analysis of percolation conduction.

Size-Dependent Valence and Conduction Band-Edge Energies of Semiconductor Nanocrystals

ACS Nano ◽  
2011 ◽  
Vol 5 (7) ◽  
pp. 5888-5902 ◽  
Author(s):  
Jacek Jasieniak ◽  
Marco Califano ◽  
Scott E. Watkins
Keyword(s):  
Conduction Band ◽  
Semiconductor Nanocrystals ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Size Dependent

Role of Surface Band Gap Widening in Cu(In, Ga)(Se, S)2 Thin-Films for the Photovoltaic Performance of ZnO/CdS/Cu(In, Ga)(Se, S)2 Heterojunction Solar Cells

2003 ◽  
Vol 763 ◽  
Author(s):  
U. Rau ◽  
M. Turcu
Keyword(s):  
Thin Films ◽  
Surface Layer ◽  
Solar Cells ◽  
Fermi Level ◽  
Band Gap ◽  
Photovoltaic Performance ◽  
Heterojunction Solar Cells ◽  
Fermi Level Pinning ◽  
Device Efficiency

AbstractNumerical simulations are used to investigate the role of the Cu-poor surface defect layer on Cu(In, Ga)Se2 thin-films for the photovoltaic performance of ZnO/CdS/Cu(In, Ga)Se2 heterojunction solar cells. We model the surface layer either as a material which is n-type doped, or as a material which is type-inverted due to Fermi-level pinning by donor-like defects at the interface with CdS. We further assume a band gap widening of this layer with respect to the Cu(In, Ga)Se2 bulk. This feature turns out to represent the key quality of the Cu(In, Ga)Se2 surface as it prevents recombination at the absorber/CdS buffer interface. Whether the type inversion results from n-type doping or from Fermi-level pinning is only of minor importance as long as the surface layer does not imply a too large number of excess defects in its bulk or at its interface with the normal absorber. With increasing number of those defects an n-type layer proofs to be less sensitive to material deterioration when compared to the type-inversion by Fermi-level pinning. For wide gap chalcopyrite solar cells the internal valence band offset between the surface layer and the chalcopyrite appears equally vital for the device efficiency. However, the unfavorable band-offsets of the ZnO/CdS/Cu(In, Ga)Se2 heterojunction limit the device efficiency because of the deterioration of the fill factor.

scholarly journals Photocatalytic properties of a new Z-scheme system BaTiO3/In2S3 with a core–shell structure

RSC Advances ◽  
2019 ◽  
Vol 9 (20) ◽  
pp. 11377-11384 ◽  
Author(s):  
Kaili Wei ◽  
Baolai Wang ◽  
Jiamin Hu ◽  
Fuming Chen ◽  
Qing Hao ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Valence Band ◽  
Conduction Band ◽  
Shell Structure ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Core Shell ◽  
Valence Band Edge ◽  
Core Shell Structure ◽  
Positive Valence

It's highly desired to design an effective Z-scheme photocatalyst with excellent charge transfer and separation, a more negative conduction band edge (ECB) than O2/·O2− (−0.33 eV) and a more positive valence band edge (EVB) than ·OH/OH− (+2.27 eV).

Sign in / Sign up

Export Citation Format

Share Document