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.

scholarly journals A Fundamental Reason for the Need of Two Different Semiconductor Technologies for Complementary Thin-Film Transistor Operations

Crystals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 603
Author(s):  
Jang ◽  
Lee
Keyword(s):  
Work Function ◽  
Thin Film Transistor ◽  
Inorganic Materials ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Valence Band Edge ◽  
Metal Work Function ◽  
Fundamental Reason ◽  
P Type ◽  
Metal Work

In this short commentary, we discuss a fundamental reason why two different semiconductor technologies are needed for complementary thin-film transistor (TFT) operations. It is mainly related to an energy-level matching between the band edge of the semiconductor and the work-function energy of the metal, which is used for the source and drain electrodes. The reference energy level is determined by the energy range of work-functions of typical metals for the source and drain electrodes. With the exception of silicon, both the conduction band edge (EC) and valence band edge (EV) of a single organic or inorganic material are unlikely to match the metal work-function energy whose range is typically from –4 to –6 eV. For example, typical inorganic materials, e.g., Zn–O, have the EC of around –4.5 eV (i.e., electron affinity), so the conduction band edge is within the range of the metal work-function energy, suggesting its suitability for n-channel TFTs. On the other hand, p-type inorganic materials, such as Cu–O, have an EV of around –5.5 eV, so the valence band edge is aligned with metal work-function energy, thus the usage for p-channel TFTs. In the case of p-type and n-type organic materials, their highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO) should be aligned with metal work-function energy. For example, p-type organic material, e.g., pentacene, has a HOMO level around –5 eV, which is within the range of the metal work-function energy, implying usage for p-channel TFTs. However, its LUMO level is around –3 eV, not being aligned with the metals’ work-function energy. So it is hard to use pentacene for n-channel TFTs. Along with this, n-type organic materials (e.g., C60) should have HOMO levels within the typical metals’ work-function energy for the usage of n-channel TFT. To support this, we provide a qualitative and comparative study on electronic material properties, such as the electron affinity and band-gap of representative organic and inorganic materials, and the work-function energy of typical metals.

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

Anomalously persistent p-type behavior of WSe2 field-effect transistors by oxidized edge-induced Fermi-level pinning

2022 ◽  
Author(s):  
Tien Dat Ngo ◽  
Min Sup Choi ◽  
Myeongjin Lee ◽  
Fida Ali ◽  
Won Jong Yoo
Keyword(s):  
Fermi Level ◽  
Field Effect ◽  
Field Effect Transistors ◽  
High Mobility ◽  
Two Dimensional ◽  
Edge Contact ◽  
Fermi Level Pinning ◽  
P Type

A technique to form the edge contact in two-dimensional (2D) based field-effect transistors (FETs) has been intensively studied for the purpose of achieving high mobility and also recently overcoming the...

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).

STM studies of Fermi-level pinning on the GaAs(001) surface

1993 ◽  
Vol 344 (1673) ◽  
pp. 533-543 ◽  
Keyword(s):  
Fermi Level ◽  
Valence Band ◽  
Surface Defects ◽  
Defect Density ◽  
Valence Band Maximum ◽  
Intrinsic Defect ◽  
Fermi Level Pinning ◽  
Donor States ◽  
P Type ◽  
Surface Donor

This paper reviews recent scanning tunnelling microsopy (STM) studies of Fermi-level pinning on the surface of both n- and p-type GaAs(001). The samples are all grown by molecular beam epitaxy and have a (2 x 4)/c(2 x 8) surface reconstruction. The STM has shown that on the surface of highly doped n-type GaAs(001) there is a high density of kinks in the dimer-vacancy rows of the (2 x 4) reconstruction. These kinks are found to be surface acceptors with approximately one electron per kink. The kinks form in exactly the required number to pin the Fermi-level of n-type GaAs(001) at an acceptor level close to mid gap, irrespective of doping level. The Fermi-level position is confirmed with tunnelling spectroscopy. No similar surface donor states are found on p-type GaAs(001). In this case Fermi-level pinning results from ‘intrinsic’ surface defects such as step edges. Since this intrinsic defect density is independent of doping, at high doping levels the Fermi-level on p-type GaAs(001) moves down in the band gap towards the valence band. Tunnelling spectroscopy on p-type GaAs(001) doped 10 19 cm -3 with Be shows the Fermi-level to be 150 mV above the valence band maximum

Fermi level pinning and negative magnetoresistance in PbTe:(Mn, Cr)

2004 ◽  
Vol 38 (1) ◽  
pp. 27-30 ◽  
Author(s):  
A. V. Morozov ◽  
A. E. Kozhanov ◽  
A. I. Artamkin ◽  
E. I. Slyn’ko ◽  
V. E. Slyn’ko ◽  
...  
Keyword(s):  
Fermi Level ◽  
Negative Magnetoresistance ◽  
Fermi Level Pinning

Valence Band Edge Shifts and Charge-transfer Dynamics in Li-Doped NiO Based p-type DSSCs

2016 ◽  
Vol 188 ◽  
pp. 309-316 ◽  
Author(s):  
Lifang Wei ◽  
Linpeng Jiang ◽  
Shuai Yuan ◽  
Xin Ren ◽  
Yin Zhao ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Valence Band ◽  
Band Edge ◽  
Valence Band Edge ◽  
Charge Transfer Dynamics ◽  
P Type
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