Barrier heights of real Schottky contacts explained by metal-induced gap states and lateral inhomogeneities

1999 ◽  
Vol 17 (4) ◽  
pp. 1867 ◽  
Author(s):  
Winfried Mönch
Keyword(s):  
Schottky Contacts ◽  
Barrier Heights ◽  
Gap States

Metal Contacts on a-GaN

1996 ◽  
Vol 1 ◽  
Author(s):  
T. U. Kampen ◽  
W. Mönch
Keyword(s):  
Tight Binding ◽  
Image Force ◽  
Schottky Contacts ◽  
Metal Contacts ◽  
Zero Bias ◽  
Barrier Heights ◽  
Current Voltage ◽  
Optical Dielectric Constant ◽  
Optical Dielectric ◽  
Gap States

The Schottky barrier heights of silver and lead contacts on n-type GaN (0001) epilayers were determined from current-voltage characteristics. The zero-bias barrier heights and the ideality factors were found to be linearly correlated. Similar observations were previously reported for metal contacts on Si (111) and GaAs (110) surfaces. The barrier heights of ideal Schottky contacts are characterized by image force lowering of the barrier only. This gives an ideality factor of 1.01. From our data we obtain barrier heights of 0.82 eV and 0.73eV for ideal Ag and Pb contacts on GaN, respectively. The metal-induced gap states (MIGS) model predicts the barrier heights of ideal Schottky contacts on a given semiconductor to be linearly correlated with the electronegativities of the metals. The two important parameters of this MIGS-and-electronegativity model are the charge neutrality level (CNL) of the MIGS and a slope parameter. The CNL may be calculated from the dielectric band gap and using the empirical tight-binding method. The slope parameters are given by the optical dielectric constant of the respective semiconductor. The predictions of the MIGS model for metal/GaN contacts are confirmed by the results presented here and by barrier heights previously reported by others for Au, Ti, Pt, and Pd contacts on GaN.

Electronic Properties of Ideal and Interface-Modified Metal-Semiconductor Contacts

1995 ◽  
Vol 378 ◽  
Author(s):  
Winfried Mönch
Keyword(s):  
Experimental Data ◽  
Charge Transfer ◽  
Electronic Properties ◽  
Nearest Neighbor ◽  
Schottky Contacts ◽  
Barrier Heights ◽  
Substrate Atom ◽  
Electronegativity Difference ◽  
Semiconductor Contacts ◽  
Gap States

AbstractBarrier heights in metal-semiconductor contacts may be modified by interlayers. The effects of atomic interlayers are due to interface dipoles. With the restriction to nearest-neighbor interactions and monovalent interlayer atoms, they may be described as interface molecules which consist of an interlayer and a substrate atom. If the interlayers are thicker than a few atomic layers their two interfaces with the metal and with the semiconductor will be non-interacting. Both types of interfaces are described by the model that interface-induced gap states determine the alignment of the bands and the electronegativity difference describes the charge transfer across the interface. The present paper discusses and analyzes experimental data for H-modified diamond and silicon, Al/Si/GalnP, and metal/ Si3N4/Si Schottky contacts.

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

Barrier heights of Schottky contacts on strained AlGaN/GaN heterostructures: Determination and effect of metal work functions

2003 ◽  
Vol 82 (24) ◽  
pp. 4364-4366 ◽  
Author(s):  
Zhaojun Lin ◽  
Wu Lu ◽  
Jaesun Lee ◽  
Dongmin Liu ◽  
Jeffrey S. Flynn ◽  
...  
Keyword(s):  
Schottky Contacts ◽  
Barrier Heights ◽  
Work Functions ◽  
Metal Work

Pt Schottky contacts on Ga- and N-face surfaces of free-standing GaN

2001 ◽  
Vol 680 ◽  
Author(s):  
U. Karrer ◽  
C.R. Miskys ◽  
O. Ambacher ◽  
M. Stutzmann
Keyword(s):  
Schottky Diodes ◽  
Reverse Current ◽  
Forward Direction ◽  
Hydride Vapor Phase Epitaxy ◽  
Free Standing ◽  
Band Bending ◽  
Barrier Heights ◽  
Consistent Solution ◽  
Lift Off ◽  
Gap States

ABSTRACTThick GaN films, grown by hydride vapor phase epitaxy (HVPE), were separated from their sapphire substrate with a laser-induced lift-off process. After cleaning and polishing, these films offer the most direct way to investigate and compare the influence of crystal polarity on the electronic properties of Ga-face and N-face surfaces, respectively. Different barrier heights for Pt Schottky diodes evaporated onto Ga- and N-face GaN are determined from the dependence of the effective barrier height versus ideality factor by I-V measurements to 1.15 eV and 0.80 eV, respectively. The charge neutrality condition at the surface is modified by the spontaneous polarization due to the polarization induced bound sheet charge. This effect has to be included in the electronegativity concept of metal induced gap states (MIGS) and can also be illustrated by different band bending of the conduction and valence band, inferred from the self-consistent solution of the Schrödinger-Poisson equation. Furthermore, temperature dependent I-V characteristics are compared to simulated behavior of Schottky diodes, exhibiting excellent agreement in forward direction, but showing deviations in the reverse current.

Phase Inhomogeneity and Electrical Characteristics of Nickel Silicide Schottky Contacts Formed on 4H-SiC

2009 ◽  
Vol 615-617 ◽  
pp. 577-580 ◽  
Author(s):  
Irina P. Nikitina ◽  
Konstantin Vassilevski ◽  
Alton B. Horsfall ◽  
Nicolas G. Wright ◽  
Anthony G. O'Neill ◽  
...  
Keyword(s):  
Nickel Silicide ◽  
Schottky Contacts ◽  
Electrical Characteristics ◽  
Adhesion Layer ◽  
Temperature Range ◽  
Barrier Heights ◽  
Phase Inhomogeneity ◽  
Layer 4 ◽  
State Chemical ◽  
Nisi Phase

Nickel silicide Schottky contacts were formed on 4H-SiC by consecutive deposition of a titanium adhesion layer, 4 nm thick, and nickel, 100 nm thick, followed by annealing at temperatures from 600 to 750 °C. It was found that contacts with barrier heights of 1.45 eV, consisting mainly of NiSi phase, formed in the 600-660 °C temperature range, while annealing at around 750 °C led to the formation of Ni2Si phase with barrier heights of 1.1 eV. Annealing at intermediate temperatures resulted in the nucleation of Ni2Si grains embedded in the NiSi film which were directly observed by micro-Raman mapping. It was concluded that the thermodynamically unfavourable NiSi phase appeared in the 600-660 °C temperature range due to the fact that the solid state chemical reaction between Ni and SiC at these temperatures is controlled by nickel diffusion through the titanium barrier.

Schottky Contacts on n-InP with High Barrier Heights and Reduced Fermi-Level Pinning by a Novel In Situ Electrochemical Process

1995 ◽  
Vol 34 (Part 1, No. 2B) ◽  
pp. 1162-1167 ◽  
Author(s):  
Nan-Jian Wu ◽  
Tamotsu Hashizume ◽  
Hideki Hasegawa ◽  
Yoshihito Amemiya
Keyword(s):  
Fermi Level ◽  
Electrochemical Process ◽  
Schottky Contacts ◽  
Fermi Level Pinning ◽  
Barrier Heights
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