SURFACE EXCESS CONDUCTANCE IN GERMANIUM TUNNEL JUNCTIONS VIA SURFACE STATES

p–n junctions are examined initially and the potential distribution in the junction region is derived based on Poisson’s equation. Next the operation of the transistor is discussed, both in terms of the physics and of equivalent circuits. Potential distributions in metal–semiconductor junctions are derived and the concept of surface states is introduced. The physics of tunnel junctions is discussed in terms of their band structure. The properties of varactor diodes are described and the possibility of parametric amplification is touched upon. Further devices discussed are field effect transistors, charge-coupled devices, controlled rectifiers, and the Gunn effect. The fabrication of microelectronic circuits is discussed, followed by the more recent but related field of micro-electro-mechanical systems. The discipline of nanoelectronics is introduced including the role of carbon nanotubes. Finally, the effect of the development of semiconductor technology upon society is discussed.

Download Full-text

Bias Dependent TMR in Fe/MgO/Fe(100) Tunnel Junctions

MRS Proceedings ◽

10.1557/proc-0941-q01-03 ◽

2006 ◽

Vol 941 ◽

Author(s):

Ivan Rungger ◽

Alexandre Reily Rocha ◽

Oleg Mryasov ◽

Olle Heinonen ◽

Stefano Sanvito

Keyword(s):

Surface State ◽

First Principles ◽

Significant Contribution ◽

Tunnel Junctions ◽

Surface States ◽

Zero Bias ◽

Spin Channel ◽

Minority Spin ◽

Self Consistent ◽

Current Flows

ABSTRACTWe calculate from first principles the I-V characteristics of Fe/MgO/Fe(100) tunnel junctions. In particular we compare the zero-bias transmission with self-consistent calculations at finite bias. In the case the magnetizations of the two Fe layers are parallel to each other, at small bias there is a significant contribution to the transmission coming from the minority spin channel. This is due to a sharp resonance in the transmission coefficient close to the Fermi level, originating from a surface state. As a bias exceeding 25 mV is applied, the surface states get out of resonance and the current through the minority spin channel saturates, so that the current flows mainly through the majority channel. The same effect is not present for the antiparallel alignment of the magnetization with the net result of large TMR at low bias, which then saturates for a bias larger than 25 mV.

Download Full-text

Determination of surface states distribution in a-Si:H using MOS tunnel Junctions

Journal of Electronic Materials ◽

10.1007/bf02652897 ◽

1980 ◽

Vol 9 (4) ◽

pp. 797-818 ◽

Cited By ~ 4

Author(s):

I. Balberg

Keyword(s):

Tunnel Junctions ◽

Surface States

Download Full-text

Interplay between topological surface states and superconductivity in SmB6/NbN tunnel junctions

Physical Review B ◽

10.1103/physrevb.96.165408 ◽

2017 ◽

Vol 96 (16) ◽

Cited By ~ 2

Author(s):

Zhu Lin ◽

Yong Zhou ◽

Ling-Jian Kong ◽

Dongsheng Tang ◽

Hai-Zhou Lu ◽

...

Keyword(s):

Tunnel Junctions ◽

Surface States ◽

Topological Surface

Download Full-text

Zero-loss omega-filtered REM and RHEED on the new Zeiss 912

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087392 ◽

1991 ◽

Vol 49 ◽

pp. 616-617

Author(s):

J.C.H. Spence ◽

J. Mayer

Keyword(s):

Electron Microscopy ◽

Materials Science ◽

Surface States ◽

Ccd Camera ◽

Dark Field ◽

Ion Pump ◽

Magnetic Imaging ◽

Reflection Electron Microscopy ◽

Diffraction Patterns ◽

Large Background

The Zeiss 912 is a new fully digital, side-entry, 120 Kv TEM/STEM instrument for materials science, fitted with an omega magnetic imaging energy filter. Pumping is by turbopump and ion pump. The magnetic imaging filter allows energy-filtered images or diffraction patterns to be recorded without scanning using efficient parallel (area) detection. The energy loss intensity distribution may also be displayed on the screen, and recorded by scanning it over the PMT supplied. If a CCD camera is fitted and suitable new software developed, “parallel ELS” recording results. For large fields of view, filtered images can be recorded much more efficiently than by Scanning Reflection Electron Microscopy, and the large background of inelastic scattering removed. We have therefore evaluated the 912 for REM and RHEED applications. Causes of streaking and resonance in RHEED patterns are being studied, and a more quantitative analysis of CBRED patterns may be possible. Dark field band-gap REM imaging of surface states may also be possible.

Download Full-text