Negative Electron Affinity Effects And Schottky Barrier Height Measurements Of Metals On Diamond (100) Surfaces

1995 ◽  
Vol 416 ◽  
Author(s):  
P. K. Baumann ◽  
R. J. Nemanich
Keyword(s):  
Schottky Barrier ◽  
Electron Affinity ◽  
Metal Layer ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Negative Electron Affinity ◽  
Barrier Heights ◽  
Diamond Crystals ◽  
Natural Type ◽  
Semiconducting Diamond

ABSTRACTIn this study copper and cobalt films have been deposited on natural type IIb single crystal semiconducting diamond (100) surfaces in ultra-high vacuum (UHV). Prior to metal deposition the diamond crystals have been cleaned by a 1150°C anneal in UHV. This treatment resulted in positive electron affinity surfaces. Upon deposition of 2Å of Cu or Co a negative electron affinity (NEA) was observed. Schottky barrier heights of 0.70 eV and 0.35 eV were found for Cu and Co respectively. In-situ Auger electron spectroscopy (AES) was employed to confirm the presence of a metal layer.

CoSi2/Si(111) Interface Structure and its Influence on the Schottky Barrier

1993 ◽  
Vol 320 ◽  
Author(s):  
J. P. Sullivan ◽  
W. R. Graham ◽  
F. Schrey ◽  
D. J. Eaglesham ◽  
R. Kola ◽  
...  
Keyword(s):  
Schottky Barrier ◽  
Film Growth ◽  
High Vacuum ◽  
Growth Conditions ◽  
Interface Structure ◽  
Ultra High Vacuum ◽  
Plan View ◽  
Barrier Heights ◽  
Interface Reconstruction ◽  
P Type

ABSTRACTThe interface structure and Schottky barrier height Of CoSi2/Si(111) interfaces may be controlled by manipulating the thin film growth conditions. Single crystal CoSi2 films on Si(111) were prepared by ultra-high vacuum processing, analyzed electrically by currentvoltage techniques, and characterized structurally by plan-view and cross-section high resolution transmission electron microscopy (HRTEM) and transm-ission electron diffraction (TED). Interfaces exhibiting n-type barrier heights ranging from 0.27 to 0.69 eV, and p-type barrier heights ranging from 0.43 eV to over 0.71 eV were prepared -by varying the processing conditions. HRTI3M and TED revealed the existence of a √3 × √3 interface reconstruction for the low barrier n-type/high barrier p-type samples. Possible models of the interface reconstruction are discussed.

Interpretation of secondary electron contrast from negative electron affinity diamond surfaces

1995 ◽  
Vol 53 ◽  
pp. 120-121
Author(s):  
D.P. Malta ◽  
J.B. Posthill ◽  
T.P. Humphreys ◽  
R.J. Markunas
Keyword(s):  
Conduction Band ◽  
Electron Affinity ◽  
Secondary Electron ◽  
Metal Layer ◽  
Wide Band ◽  
Diamond Surface ◽  
Semiconductor Surface ◽  
Negative Electron Affinity ◽  
Diamond Surfaces ◽  
Electron Emitters

Diamond is a wide band-gap semiconductor with many unique physical properties that make it an attractive technological material. One such property is the negative electron affinity (NEA) behavior of the surface when properly terminated with hydrogen or a thin metal layer. The NEA diamond surface exhibits an unusually large secondary electron (SE) yield which is desirable for applications in cold cathode electron emitters of flat panel displays. Examination of NEA diamond surfaces by scanning electron microscopy (SEM) has indicated that a unique mechanism appears to be responsible for the SE contrast in which sub-surface microstructural information is contained. This paper provides a brief interpretation of the origin of SE contrast from the NEA diamond surface.The electron affinity of a semiconductor surface, χ, is defined by the position of the vacuum energy level, E0, relative to the conduction band minimum, Ec (Fig. la). If χ>0, excited conduction band electrons must migrate to the surface and arrive with sufficient kinetic energy to overcome the surface energy barrier in order to escape into vacuum.

Properties of Metal / Polyphenylquinoxaline Interfaces

1994 ◽  
Vol 337 ◽  
Author(s):  
L. Bellard ◽  
J.M. Themlin ◽  
F. Palmino ◽  
A. Cros
Keyword(s):  
Metal Layer ◽  
High Vacuum ◽  
Polymer Surface ◽  
Pure Metal ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Layer By Layer ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTWe have investigated the microscopic properties of copper and chromium layers deposited on polyphenylquinoxaline (PPQ). PPQ is a thermostable polymer used for multichip module applications. The metal is deposited under ultra-high vacuum conditions and analysed in-situ by X-ray photoemission (XPS) and atomic force microscopy (ex situ). Copper does not react significantly with the PPQ and tends to diffuse into the polymer matrix upon annealing. On the contrary, chromium strongly reacts with the polymer surface at room temperature. With increasing metal coverage, chromium grows in a layer-by-layer mode and the reacted interface is progressively burried under the pure metal layer.

Characterization of Zirconium - Diamond Interfaces

1996 ◽  
Vol 423 ◽  
Author(s):  
P. K. Baumann ◽  
S. P. Bozeman ◽  
B. L. Ward ◽  
R. J. Nemanich
Keyword(s):  
Electron Affinity ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Threshold Field ◽  
Diamond Surfaces ◽  
Field Emission Current ◽  
Current Voltage ◽  
Single Crystal Diamond ◽  
A Current

AbstractThin Zr films were deposited on natural single crystal diamond (100) substrates by ebeam evaporation in ultra-high vacuum (UHV). Before metal deposition the surfaces were cleaned by UHV anneals at either 500°C or 1150°C. Following either one of these treatments a positive electron affinity was determined by means of UV photoemission spectroscopy (UPS). Depositing 2Å of Zr induced a NEA on both surfaces. Field emission current - voltage measurements resulted in a threshold field (for a current of 0.1 µA) of 79 V/µm for positive electron affinity diamond surfaces and values as low as 20 V/µm for Zr on diamond.

Barrier Modification In Au/IIb Semiconducting Diamond Contacts

1995 ◽  
Vol 416 ◽  
Author(s):  
M. Teklu ◽  
K. Das
Keyword(s):  
Low Dose ◽  
Surface Preparation ◽  
Material System ◽  
Conducting Material ◽  
Doped Semiconductors ◽  
Barrier Heights ◽  
Metal Work Function ◽  
Diamond Crystals ◽  
Semiconducting Diamond ◽  
Metal Work

ABSTRACTRectifying contacts on semiconducting type IIb diamond crystals are readily established with any conducting material system including elemental metals, highly doped semiconductors, silicides and carbides. However, for a given surface preparation using oxidizing wet chemicals and in the absence of a surface reaction, barrier heights are observed to be constant regardless of the metal work function. In this report it is demonstrated that an adjustment of the barrier height can be achieved by employing a premetallization low-dose low-energy ion-implantation step.

Thin Pyrolytic Graphite Films for Electron Microscope Substrates

1971 ◽  
Vol 29 ◽  
pp. 226-227 ◽  
Author(s):  
George H. N. Riddle ◽  
Benjamin M. Siegel
Keyword(s):  
Vacuum Chamber ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Graphite Substrate ◽  
Nickel Substrate ◽  
Routine Procedure ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

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