Highly Efficient Experimental Approach to Evaluate Metal to 2D Semiconductor Interfaces in Vertical Diodes with Asymmetric Metal Contacts

The physics and technology of metal/semiconductor interfaces are key-points in the development of silicon carbide (SiC) based devices. Although in the last decade, the metal to 4H-SiC contacts, either Ohmic or Schottky type, have been extensively investigated with important achievements, these remain even now an intriguing topic since metal contacts are fundamental bricks of all electronic devices. Hence, their comprehension is at the base of the improvement of the performances of simple devices and complex systems. In this context, this paper aims to highlight some relevant aspects related to metal/semiconductor contacts to SiC, both on n-type and p-type, with an emphasis on the role of the barrier and on the carrier transport mechanisms at the interfaces.

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Highly efficient, transparent and stable semitransparent colloidal quantum dot solar cells: a combined numerical modeling and experimental approach

Energy & Environmental Science ◽

10.1039/c6ee02824a ◽

2017 ◽

Vol 10 (1) ◽

pp. 216-224 ◽

Cited By ~ 27

Author(s):

Xiaoliang Zhang ◽

Carl Hägglund ◽

Erik M. J. Johansson

Keyword(s):

Numerical Modeling ◽

Solar Cells ◽

Solar Cell ◽

Quantum Dot ◽

Experimental Approach ◽

High Efficiency ◽

Highly Efficient ◽

Quantum Dot Solar Cells ◽

Colloidal Quantum Dot ◽

Experimental Approaches

A semitransparent colloidal quantum dot solar cell with high efficiency, transparency and stability is reported by coupling numerical modeling and experimental approaches.

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Electronic properties of semiconductor interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126470 ◽

1987 ◽

Vol 45 ◽

pp. 334-337

Author(s):

Jerry Woodall

Keyword(s):

Fermi Level ◽

Electronic Properties ◽

Significant Role ◽

High Speed ◽

Laboratory Scale ◽

Metal Contacts ◽

Manufacturing Environment ◽

The Past ◽

Semiconductor Interfaces ◽

Dielectric Interfaces

Over the past decade III-V materials have been successfully commercialized for optoelectronic applications requiring LED's lasers and photodetectors. The success of these materials for these applications is based primarily on the use of heterojunction structures formed by epitaxial techniques in a manufacturing environment. More recently, III-V materials, notably GaAs, have been studied in the R&D environment as possible materials for use in high speed devices and circuits including VLSI. Even though the use of epitaxially grown structures has played a significant role in the success of laboratory scale devices and circuits, there are still several technology problems which will need to be solved before affordable manufacturing can be done. Two important challenges facing the commercialization of these materials for this application are metal contacts, and dielectrics for control and passivation. Both of these challenges are rooted in a common problem. Stated simply, the problem is that at nearly all GaAs/metal or dielectric interfaces the Fermi level is pinned near mid-gap.

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The study of interfacial reactions of nickel thin films on GaAs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074616 ◽

1983 ◽

Vol 41 ◽

pp. 156-157

Author(s):

L.J. Chen ◽

Y.F. Hsieh

Keyword(s):

Thin Films ◽

Integrated Circuits ◽

Interfacial Reactions ◽

Metal Contacts ◽

Nickel Thin Films ◽

Thin Foils ◽

The Status ◽

Si Doped ◽

Electron Microscopes

One measure of the maturity of a device technology is the ease and reliability of applying contact metallurgy. Compared to metal contact of silicon, the status of GaAs metallization is still at its primitive stage. With the advent of GaAs MESFET and integrated circuits, very stringent requirements were placed on their metal contacts. During the past few years, extensive researches have been conducted in the area of Au-Ge-Ni in order to lower contact resistances and improve uniformity. In this paper, we report the results of TEM study of interfacial reactions between Ni and GaAs as part of the attempt to understand the role of nickel in Au-Ge-Ni contact of GaAs.N-type, Si-doped, (001) oriented GaAs wafers, 15 mil in thickness, were grown by gradient-freeze method. Nickel thin films, 300Å in thickness, were e-gun deposited on GaAs wafers. The samples were then annealed in dry N2 in a 3-zone diffusion furnace at temperatures 200°C - 600°C for 5-180 minutes. Thin foils for TEM examinations were prepared by chemical polishing from the GaA.s side. TEM investigations were performed with JE0L- 100B and JE0L-200CX electron microscopes.

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Experimental Determination of the Effective Resolution Limit in Thick Specimens at High Voltages

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100116942 ◽

1975 ◽

Vol 33 ◽

pp. 664-665

Author(s):

Mircea Fotino

Keyword(s):

Experimental Approach ◽

Chromatic Aberration ◽

Resolving Power ◽

Biological Research ◽

Specimen Thickness ◽

Resolution Limit ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

Resolution Level

The use of thick specimens (0.5 μm to 5.0 μm or more) is one of the most resourceful applications of high-voltage electron microscopy in biological research. However, the energy loss experienced by the electron beam in the specimen results in chromatic aberration and thus in a deterioration of the effective resolving power. This sets a limit to the maximum usable specimen thickness when investigating structures requiring a certain resolution level.An experimental approach is here described in which the deterioration of the resolving power as a function of specimen thickness is determined. In a manner similar to the Rayleigh criterion in which two image points are considered resolved at the resolution limit when their profiles overlap such that the minimum of one coincides with the maximum of the other, the resolution attainable in thick sections can be measured by the distance from minimum to maximum (or, equivalently, from 10% to 90% maximum) of the broadened profile of a well-defined step-like object placed on the specimen.

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An atomic-resolution microscope study of Al contracts on GaAs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100145005 ◽

1986 ◽

Vol 44 ◽

pp. 726-727

Author(s):

Z. Liliental-Weber ◽

C. Nelson ◽

R. Ludeke ◽

R. Gronsky ◽

J. Washburn

Keyword(s):

High Speed ◽

Schottky Contacts ◽

Detailed Knowledge ◽

The Past ◽

Semiconductor Interfaces ◽

Deposited Metal ◽

Microwave Applications ◽

Free Interfaces ◽

Potential Use

The properties of metal/semiconductor interfaces have received considerable attention over the past few years, and the Al/GaAs system is of special interest because of its potential use in high-speed logic integrated optics, and microwave applications. For such materials a detailed knowledge of the geometric and electronic structure of the interface is fundamental to an understanding of the electrical properties of the contact. It is well known that the properties of Schottky contacts are established within a few atomic layers of the deposited metal. Therefore surface contamination can play a significant role. A method for fabricating contamination-free interfaces is absolutely necessary for reproducible properties, and molecularbeam epitaxy (MBE) offers such advantages for in-situ metal deposition under UHV conditions

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The morphologies and electrical properties of indium contacts on (100) cadmium telluride surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131747 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1422-1423

Author(s):

A.M. Letsoalo ◽

M.E. Lee ◽

E.O. de Neijs

Keyword(s):

Electrical Properties ◽

Cadmium Telluride ◽

Methanol Solution ◽

Electrical Characteristics ◽

Metal Contacts ◽

Deposition Technique ◽

Interfacial Layers ◽

Semiconductor Contacts ◽

Grown Single Crystal ◽

Diamond Abrasive

Semiconductor devices require metal contacts for efficient collection of electrical charge. The physics of these metal/semiconductor contacts assumes perfect, abrupt and continuous interfaces between the layers. However, in practice these layers are neither continuous nor abrupt due to poor nucleation conditions and the formation of interfacial layers. The effects of layer thickness, deposition rate and substrate stoichiometry have been previously reported. In this work we will compare the effects of a single deposition technique and multiple depositions on the morphology of indium layers grown on (100) CdTe substrates. The electrical characteristics and specific resistivities of the indium contacts were measured, and their relationships with indium layer morphologies were established.Semi-insulating (100) CdTe samples were cut from Bridgman grown single crystal ingots. The surface of the as-cut slices were mechanically polished using 5μm, 3μm, 1μm and 0,25μm diamond abrasive respectively. This was followed by two minutes immersion in a 5% bromine-methanol solution.

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High-resolution z-contrast imaging of semiconductor interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154317 ◽

1989 ◽

Vol 47 ◽

pp. 468-469

Author(s):

S. J. Pennycook

Keyword(s):

High Resolution ◽

Phase Contrast ◽

Contrast Imaging ◽

Compositional Modulation ◽

Semiconductor Interfaces ◽

Complex Figure ◽

Thin Region ◽

Stem Image ◽

Annular Detector ◽

Z Contrast

Using a high-angle annular detector on a high-resolution STEM it is possible to form incoherent images of a crystal lattice characterized by strong atomic number or Z contrast. Figure 1 shows an epitaxial Ge film on Si(100) grown by oxidation of Ge-implanted Si. The image was obtained using a VG Microscopes' HB501 STEM equipped with an ultrahigh resolution polepiece (Cs ∽1.2 mm, demonstrated probe FWHM intensity ∽0.22 nm). In both crystals the lattice is resolved but that of Ge shows much brighter allowing the interface to be located exactly and interface steps to be resolved (arrowed). The interface was indistinguishable in the phase-contrast STEM image from the same region, and even at higher resolution the location of the interface is complex. Figure 2 shows a thin region of an MBE-grown ultrathin super-lattice (Si8Ge2)100. The expected compositional modulation would show as one bright row of dots from the 2 Ge monolayers separated by 4 rows of lighter Si columns. The image shows clearly that strain-induced interdiffusion has occurred on the monolayer scale.

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Highly efficient and selective photocatalytic CO2 to CO conversion in aqueous solution

Chemical Communications ◽

10.1039/d0cc00879f ◽

2020 ◽

Vol 56 (27) ◽

pp. 3851-3854 ◽

Cited By ~ 6

Author(s):

Xiaomin Chai ◽

Hai-Hua Huang ◽

Huiping Liu ◽

Zhuofeng Ke ◽

Wen-Wen Yong ◽

...

Keyword(s):

Aqueous Solution ◽

Photocatalytic Performance ◽

Aqueous Media ◽

Highly Efficient ◽

Co Conversion

A Co-based complex displayed the highest photocatalytic performance for CO2 to CO conversion in aqueous media.

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Tuning the pore structures and photocatalytic properties of a 2D covalent organic framework with multi-branched photoactive moieties

Nanoscale ◽

10.1039/d0nr02994g ◽

2020 ◽

Vol 12 (30) ◽

pp. 16136-16142

Author(s):

Xuan Wang ◽

Ming-Jie Dong ◽

Chuan-De Wu

Keyword(s):

Photocatalytic Properties ◽

Effective Strategy ◽

Covalent Organic Framework ◽

Highly Efficient ◽

Pore Structures ◽

Local Connection ◽

Organic Framework

An effective strategy to incorporate accessible metalloporphyrin photoactive sites into 2D COFs by establishing a 3D local connection for highly efficient photocatalysis was developed.

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