Semiconductor Electrodes: XLII . Evidence for Fermi Level Pinning from Shifts in the Flatband Potential of p‐Type Silicon in Acetonitrile Solutions with Different Redox Couples

1982 ◽  
Vol 129 (8) ◽  
pp. 1742-1745 ◽  
Author(s):  
G. Nagasubramanian ◽  
Bob L. Wheeler ◽  
Fu‐Ren F. Fan ◽  
Allen J. Bard
Author(s):  
Tien Dat Ngo ◽  
Min Sup Choi ◽  
Myeongjin Lee ◽  
Fida Ali ◽  
Won Jong Yoo

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...


1989 ◽  
Vol 67 (3) ◽  
pp. 382-388 ◽  
Author(s):  
O. Savadogo

Modification of several semiconductors material surfaces with H4SiW12O40•nH2O have been carried out to produce an increase in the open circuit photopotential at the semiconductor/electrolyte interface (Voc) without changing the flat-band potential. The augmentation of Voc is shown to be attributed to a decrease of the minority carriers recombination at the semiconductor/electrolyte interface along with the suppression of Fermi level pinning. The enhancement of Voc and the electrocatalytic activity of the hydrogen evolution reaction in acidic medium of the derivatized electrodes is attributed to the Fermi level unpinning. Keywords: photoelectrodes, photoelectrocatalysis, pinning, modification improvement.


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


2002 ◽  
Vol 16 (20n22) ◽  
pp. 3343-3346 ◽  
Author(s):  
D. KHOKHLOV ◽  
I. IVANCHIK ◽  
A. KOZHANOV ◽  
A. MOROZOV ◽  
E. SLYNKO ◽  
...  

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.


2008 ◽  
Vol 85 (1) ◽  
pp. 2-8 ◽  
Author(s):  
Huang-Chun Wen ◽  
Prashant Majhi ◽  
Kisik Choi ◽  
C.S. Park ◽  
Husam N. Alshareef ◽  
...  

1980 ◽  
Vol 1 ◽  
Author(s):  
J. C. C. Fan ◽  
R. L. Chapman ◽  
J. P. Donnelly ◽  
G. W. Turner ◽  
C. O. Bozler

ABSTRACTA scanned cw Nd: YAG laser was used to anneal ion-implanted GaAs and InP wafers. Measurements show that electrical activation is greater for p-type than for n-type dopants in GaAs, while in InP, the opposite is observed. A simple Fermi-level pinning model is presented to explain not only the electrical properties we have measured, but also those observed by other workers. We have fabricated GaAs and InP solar cells with junctions formed by ion implantation followed by laser annealing. The GaAs cells have much better conversion efficiencies than the InP cells, and this difference can be explained in terms of the model.


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