Fermi Level Pinning and Orbital Polarization Effects in Molecular Junctions: The Role of Metal Induced Gap States

2014 ◽  
Vol 24 (39) ◽  
pp. 6154-6165 ◽  
Author(s):  
Colin Van Dyck ◽  
Victor Geskin ◽  
Jérôme Cornil
Keyword(s):  
Fermi Level ◽  
Molecular Junctions ◽  
Polarization Effects ◽  
Fermi Level Pinning ◽  
Gap States

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.

Gap state distribution and Fermi level pinning in monolayer to multilayer MoS2 field effect transistors

Nanoscale ◽  
2020 ◽  
Vol 12 (16) ◽  
pp. 8883-8889 ◽  
Author(s):  
Ronen Dagan ◽  
Yonatan Vaknin ◽  
Yossi Rosenwaks
Keyword(s):  
Transition Metal ◽  
Fermi Level ◽  
Field Effect ◽  
Field Effect Transistors ◽  
High Surface ◽  
Volume Ratio ◽  
Transition Metal Dichalcogenide ◽  
State Distribution ◽  
Fermi Level Pinning ◽  
Gap States

Gap states and Fermi level pinning play an important role in all semiconductor devices, but even more in transition metal dichalcogenide-based devices due to their high surface to volume ratio and the absence of intralayer dangling bonds.

Increase in Schottky Barrier Height in the CoSi2/Si (100) Interface Caused by Hydrogen

1992 ◽  
Vol 281 ◽  
Author(s):  
A. D. Marwick ◽  
M. O. Aboelfotoh ◽  
R. Casparis
Keyword(s):  
Fermi Level ◽  
Schottky Barrier ◽  
Barrier Height ◽  
Schottky Barrier Height ◽  
Interface States ◽  
Hydrogen Atoms ◽  
Fermi Level Pinning ◽  
Gap States

ABSTRACTIt is shown that the presence of 8 × 1015 hydrogen atoms/cm2 in the CoSi2/Si (100) interface causes an increase in the Schottky barrier height of 120 meV, and that passivation of dopants in the substrate is not the cause of this change. The data is evidence that the position of the Fermi level in this interface is controlled by defect-related interface states. After hydrogenation the Schottky barrier height agrees with that predicted by theory for Fermi level pinning by virtual gap states of the silicon.

scholarly journals Assessing the role of hydrogen in Fermi-level pinning in chalcopyrite and kesterite solar absorbers from first-principles calculations

2018 ◽  
Vol 123 (16) ◽  
pp. 161408 ◽  
Author(s):  
J. B. Varley ◽  
V. Lordi ◽  
T. Ogitsu ◽  
A. Deangelis ◽  
K. Horsley ◽  
...  
Keyword(s):  
Fermi Level ◽  
First Principles ◽  
First Principles Calculations ◽  
Fermi Level Pinning ◽  
Solar Absorbers

Fermi Level Pinning by Gap States in Organic Semiconductors

2013 ◽  
Vol 110 (3) ◽  
Author(s):  
S. Yogev ◽  
R. Matsubara ◽  
M. Nakamura ◽  
U. Zschieschang ◽  
H. Klauk ◽  
...  
Keyword(s):  
Fermi Level ◽  
Organic Semiconductors ◽  
Fermi Level Pinning ◽  
Gap States

scholarly journals Van der Waals metal-semiconductor junction: Weak Fermi level pinning enables effective tuning of Schottky barrier

2016 ◽  
Vol 2 (4) ◽  
pp. e1600069 ◽  
Author(s):  
Yuanyue Liu ◽  
Paul Stradins ◽  
Su-Huai Wei
Keyword(s):  
Fermi Level ◽  
Schottky Barrier ◽  
Van Der Waals ◽  
Two Dimensional ◽  
Fermi Level Pinning ◽  
Fundamental Properties ◽  
2D Semiconductors ◽  
Semiconductor Junction ◽  
Device Applications ◽  
Gap States

Two-dimensional (2D) semiconductors have shown great potential for electronic and optoelectronic applications. However, their development is limited by a large Schottky barrier (SB) at the metal-semiconductor junction (MSJ), which is difficult to tune by using conventional metals because of the effect of strong Fermi level pinning (FLP). We show that this problem can be overcome by using 2D metals, which are bounded with 2D semiconductors through van der Waals (vdW) interactions. This success relies on a weak FLP at the vdW MSJ, which is attributed to the suppression of metal-induced gap states. Consequently, the SB becomes tunable and can vanish with proper 2D metals (for example, H-NbS2). This work not only offers new insights into the fundamental properties of heterojunctions but also uncovers the great potential of 2D metals for device applications.

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