Evidence of electric field-tunable tunneling probability in graphene and metal contact

Nanoscale ◽  
2017 ◽  
Vol 9 (27) ◽  
pp. 9520-9528 ◽  
Author(s):  
Songang Peng ◽  
Zhi Jin ◽  
Dayong Zhang ◽  
Jingyuan Shi ◽  
Yanhui Zhang ◽  
...  
Keyword(s):  
Electric Field ◽  
Fermi Level ◽  
Tunneling Probability ◽  
Metal Contact

The tunneling probability in metal/graphene contact is not constant, but highly dependent on the Fermi level of graphene under the metal.

Field-assisted ionization theory for microscopists

1994 ◽  
Vol 52 ◽  
pp. 820-821
Author(s):  
Patrick P. Camus
Keyword(s):  
Electric Field ◽  
Electron Tunneling ◽  
Ionization Probability ◽  
Critical Distance ◽  
Tunneling Probability ◽  
Field Ionization ◽  
Radius Of Curvature ◽  
Field Evaporation ◽  
A Value ◽  
Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

Dependence of Reliability of Ultrathin Mos Gate Oxides on the Fermi Level Positions at Gate and Substrate

1997 ◽  
Vol 473 ◽  
Author(s):  
Tien-Chun Yang ◽  
Navakanta Bhat ◽  
Krishna C. Saraswat
Keyword(s):  
Electric Field ◽  
Fermi Level ◽  
Breakdown Strength ◽  
Gate Oxide ◽  
High Energy ◽  
Constant Current ◽  
Oxide Breakdown ◽  
Mos Devices ◽  
High Energy Electrons ◽  
Substrate Doping

ABSTRACTWe demonstrate that the reliability of ultrathin (< 10 nm) gate oxide in MOS devices depends on the Fermi level position at the gate, and not on the position at the substrate for constant current gate injection (Vg-). The oxide breakdown strength (Qbd) is less for p+ poly-Si gate than for n+ poly-Si gate, but, it is independent of the substrate doping type. The degradation of oxides is closely related to the electric field across the gate oxide, which is influenced by the cathode Fermi level. P+ poly-Si gate has higher barrier height for tunneled electrons, therefore, the cathode electric field must be higher to give the same injection current density. A higher electric field gives more high energy electrons at the anode, and therefore the damage is more at the substrate interface. Different substrate types cause no effect on the oxide electric field, and as a result, they do not influence the degradation.

Position of fermi level on Al0.2Ga0.8N surface and distribution of electric field in Al0.2Ga0.8N/GaN heterostructures without and with AlN layer

2014 ◽  
Vol 115 (13) ◽  
pp. 133504 ◽  
Author(s):  
M. Gladysiewicz ◽  
L. Janicki ◽  
R. Kudrawiec ◽  
J. Misiewicz ◽  
M. Wosko ◽  
...  
Keyword(s):  
Electric Field ◽  
Fermi Level ◽  
Distribution Of Electric Field

Fermi-Level effect and junction carrier concentration effect on p-Type dopant distribution in IlI-V Compound superlattices

1998 ◽  
Vol 535 ◽  
Author(s):  
Chang-Ho Chen ◽  
Ulrich M. Gösele ◽  
Teh Y. Tan
Keyword(s):  
Electric Field ◽  
Fermi Level ◽  
Hole Concentration ◽  
Equilibrium Concentration ◽  
Dopant Atom ◽  
Group Iii ◽  
Atom Diffusion ◽  
Segregation Phenomenon ◽  
P Type ◽  
Positively Charged

AbstractThe pronounced segregation phenomenon in the distribution of p-type dopants Zn and Be in GaAs and related III-V compound heterostructures has been explained quantitatively by treating simultaneously the processes of dopant atom diffusion, segregation, and the effect of heterojunction carrier concentrations on these two aspects. Segregation of a dopant species between two semiconductor heterostructure layers is described by a model incorporating (i) a chemical effect on the neutral species; and (ii) in addition, a Fermi-level effect on the ionized species. The process of Zn and Be diffusion in GaAs and related compounds is governed by the doubly-positively-charged group III element self-interstitials whose thermal equilibrium concentration and hence also the Zn and Be diffusivities exhibit also a Fermi-level dependence, i.e., in proportion to p2.A heterojunction is consisting of a space charge region with an electric field, in which the hole concentration is different from those in the bulk layers. This influences the junction region concentrations of and of Zn− or Be−, which in turn influence the distribution of the ionized acceptor atoms. The overall process involves diffusion and segregation of holes, , Zn− or Be−, and an ionized interstitial acceptor species. The junction electric field also changes with time and position.

C-V and G-V Measurements Showing Single Electron Trapping in Nanocrystalline Silicon Dot Embedded in MOS Memory Structure

2001 ◽  
Vol 686 ◽  
Author(s):  
Shaoyun Huang ◽  
Souri Banerjee ◽  
Shunri Oda
Keyword(s):  
Electric Field ◽  
Thermal Activation ◽  
Room Temperature ◽  
Nanocrystalline Silicon ◽  
Tunneling Probability ◽  
Activation Mechanism ◽  
Flat Band ◽  
Memory Retention ◽  
Charge Loss ◽  
Nanocrystalline Si

AbstractWe prepared a SiO2/nanocrystalline Si (nc-Si)/SiO2 sandwich structure. A clear positive shift in C-V and G-V curves due to electrons trapped in nc-Si dots has been observed at room temperature. The peak in conductance around flat band condition indicates that a trap event had occurred where an electron is stored per nc-Si dot. A logarithmic charge loss function is found and this discharging process is independent of the thermal activation mechanism. The longer memory retention time and logarithmic charge loss in the dots are explained by a “built-in” electric field through the tunnel oxide, which varies with time, resulting in a variable tunneling probability. The electric repulsion induced by the built-in electric field hinders the discharging of electrons remained in the dots.

scholarly journals Effect of Graphene Doping Level near the Metal Contact Region on Electrical and Photoresponse Characteristics of Graphene Photodetector

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4661
Author(s):  
Jaedong Jung ◽  
Honghwi Park ◽  
Heungsup Won ◽  
Muhan Choi ◽  
Chang-Ju Lee ◽  
...  
Keyword(s):  
Electric Field ◽  
Doping Level ◽  
High Speed ◽  
High Performance ◽  
Contact Region ◽  
Metal Contact ◽  
Electrical Characteristics ◽  
Short Channel ◽  
Level Difference ◽  
Graphene Doping

Graphene-metal contact is crucial to fabricate high-performance graphene photodetectors since the external quantum efficiency (EQE) of the photodetector depends on the contact properties, and the influence of the contact properties is particularly dominant in short channel devices for high-speed applications. Moreover, junction properties between the channel graphene and graphene near the contact are also important to analyze the photoresponse because the built-in electric field in the junction determines the EQE of the photodetector. In this study, we investigated a relation between the photoresponse and the built-in electric field induced from the doping level difference in the junction between the channel graphene and graphene near the contact. The photoresponse could be enhanced with a high junction barrier height that is tuned by the doping level difference. In addition, we observed that the improved electrical characteristics of channel graphene do not guarantee the enhancement of the photoresponse characteristics of graphene photodetectors.

Investigation on field-emission properties of graphdiyne–ZnO composite

2018 ◽  
Vol 32 (24) ◽  
pp. 1850285 ◽  
Author(s):  
Xiaoming Yuan ◽  
Yanqi Yang ◽  
Juan Guo ◽  
Daohan Ge ◽  
Ping Yang
Keyword(s):  
Binding Energy ◽  
Electric Field ◽  
Fermi Level ◽  
Field Emission ◽  
Electronic Structures ◽  
Composite Model ◽  
High Binding Energy ◽  
Emission Properties ◽  
Field Emission Properties ◽  
Work Functions

Graphdiyne–ZnO composite is constructed to investigate field-emission. We hope the tip effect of graphdiyne can be strengthened by doping ZnO. We find that the effective movement of the Fermi level and the dwindling of band gap have contributed to the modification of the electronic structures of this composite significantly with increase in the electric field. The high binding energy indicates that the composite model is very stable. In addition, the ionization energies and work functions decrease linearly with the increasing electric field, which represents an improvement of field-emission properties. It implies that graphdiyne–ZnO composite may become a promising material for field-emission.

Electric field emission of electrons from negatively charged spherical particles in a dusty plasma in the regime of nonlinear screening

2010 ◽  
Vol 88 (8) ◽  
pp. 617-621 ◽  
Author(s):  
Gyan Prakash
Keyword(s):  
Potential Energy ◽  
Electric Field ◽  
Dusty Plasma ◽  
Field Emission ◽  
Energy Barrier ◽  
Tunneling Probability ◽  
Spherical Particles ◽  
Potential Energy Barrier ◽  
The Matrix ◽  
Field Emission Of Electrons

This note presents a discussion of the electric field emission from negatively charged spherical particles in a dusty plasma in the regime of nonlinear screening. Using the appropriate representation of the nonlinear screening by Gurevich and the matrix method, the tunneling probability of an electron through the potential energy barrier around the particle has been evaluated as a function of its radial energy; corresponding values of the current density have also been obtained. A discussion of numerical results, thus obtained concludes the presentation.

Fermi-Level Effect, Electric Field Effect, and Diffusion Mechanisms in GaAs Based III-V Compound Semiconductors

1998 ◽  
Vol 527 ◽  
Author(s):  
T. Y. Tan ◽  
C.-H. Chen ◽  
U. Gösele ◽  
R. Scholz
Keyword(s):  
Electric Field ◽  
Fermi Level ◽  
Point Defects ◽  
Field Effect ◽  
Pressure Effect ◽  
Electric Field Effect ◽  
Diffusion Mechanisms ◽  
And Diffusion ◽  
Level Effect

ABSTRACTDiffusion mechanisms and point defects in GaAs and related III-V compounds are discussed. An understanding of the As sublattice situation has been arrived at fairly recently and is presently tentative. Understanding of the Ga sublattice situation has become more acceptable in that experimental results are consistently explained by the Fermi-level effect and the As4 pressure effect. On the Ga sublattice, though controversies still exist, some are readily resolved by noting the role of the electric field produced by semiconductor electrical junctions, physical junctions, and surfaces.

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