A Novel Method for True Work Function Determination of Metal Surfaces by Combined Kelvin Probe and Photoelectric Effect Measurements

2000 ◽  
Vol 619 ◽  
Author(s):  
Bert Lägel ◽  
Iain D. Baikie ◽  
Konrad Dirscherl ◽  
Uwe Petermann
Keyword(s):  
Thin Film ◽  
Work Function ◽  
Metal Surfaces ◽  
Surface Condition ◽  
High Vacuum ◽  
Photoelectric Effect ◽  
Ultra High Vacuum ◽  
Kelvin Probe ◽  
Novel Method

ABSTRACTWe have developed a novel method for in-situ measurements of the true work function (ø) of metal surfaces by combined ultra-high vacuum compatible Kelvin Probe and photoelectric effect measurements. The work function is an extremely sensitive parameter of surface condition and can be used to study oxidation and thin film growth on metal surfaces. For example, the increase in ø due to oxidation of polycrystalline rhenium is 1.9eV.The Kelvin Probe measures local work function differences between a conducting sample and a reference tip in a non-contact, truly non-invasive way over a wide temperature range. However, it is an inherently relative technique and does not provide an absolute work function if the work function of the tip (øtip) is unknown.We present a novel approach to measure øtip with the Kelvin Probe via the photoelectric effect, using a Gd foil as the photoelectron source, hereby combining the advantages of both methods to provide the absolute work function of the sample surface. We demonstrate the application of the technique by in-situ work function measurements during oxidation of polycrystalline rhenium. The extended Kelvin Probe method therefore has potential applications as a characterisation tool for thin film epitaxy and work function engineering of surfaces.

A Novel Approach for True Work Function Determination of Electron-Emissive Materials by Combined Kelvin Probe and Photoelectric Effect Measurements

2000 ◽  
Vol 621 ◽  
Author(s):  
Bert Lägel ◽  
Iain D. Baikie ◽  
Konrad Dirscherl ◽  
Uwe Petermann
Keyword(s):  
Work Function ◽  
High Vacuum ◽  
Sample Surface ◽  
Photoelectric Effect ◽  
Ultra High Vacuum ◽  
Chemical Contamination ◽  
Kelvin Probe ◽  
Non Invasive ◽  
Novel Approach ◽  
The Stability

ABSTRACTFor the development of new electron-emissive materials knowledge of the work function Φ and changes in Φ is of particular interest. Among the various methods, the ultra-high vacuum (UHV) compatible scanning Kelvin Probe has been proven to be a superior technique to measure work function changes due to e.g. UHV cleaning processes, chemical contamination, thermal processing etc. with high accuracy (<1meV).The Kelvin Probe measures local work function differences between a conducting sample and a reference tip in a non-contact, truly non-invasive way over a wide temperature range. However, it is an inherently relative technique and does not provide an absolute work function if the work function of the tip (Φtip) is unknown.Here, we present a novel approach to measure Φtip with the Kelvin Probe via the photoelectric effect, where a Gd foil is used as the photoelectron source. This method thus provides the true work function of the sample surface with an accuracy of approx. 50meV. We demonstrate the application of the technique by in situ work function measurements on evaporated layers of the low work function material LaB6 on a Re substrate and follow the changes in Φ of LaB6 due to the surface adsorption of residual gas molecules. Thus, the extended Kelvin Probe method provides an excellent tool to characterise and monitor the stability of low work function surfaces.

Work function study of rhenium oxidation using an ultra high vacuum scanning Kelvin probe

2000 ◽  
Vol 88 (7) ◽  
pp. 4371 ◽  
Author(s):  
I. D. Baikie ◽  
U. Petermann ◽  
A. Speakman ◽  
B. Lägel ◽  
K. M. Dirscherl ◽  
...  
Keyword(s):  
Work Function ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Kelvin Probe ◽  
Function Study ◽  
Scanning Kelvin Probe

UHV In-Situ Electron Microscopy of thin Film Growth

1976 ◽  
Vol 34 ◽  
pp. 442-443
Author(s):  
K. Yagi ◽  
K. Takayanagi ◽  
K. Kobayashi ◽  
G. Honjo
Keyword(s):  
Thin Film ◽  
Film Growth ◽  
High Vacuum ◽  
Dendritic Morphology ◽  
Thin Film Growth ◽  
Ultra High Vacuum ◽  
In Situ Studies ◽  
In Situ Electron Microscopy ◽  
Dendritic Shape

An ultra-high vacuum (UHV) electron microscope was constructed for special purpose of in-situ studies of thin film growth and some experimental results have already been published (1). Here, recent results are described.1. Au/graphite (nucleation and growth mode). Growths of Au in a dendritic shape at 150°C were observed on graphite. The dendritic morphology was said to be characteristic of the Au growth on UHV cleaved graphite (2). We cleaned an air cleaved surface by heating in UHV EM (10-8 torr) for 20 minutes prior to the Au deposition. The dendritic shape growth in Fig. 1, therefore, indicates that the graphite surface became clean with the present heat treatment and that the in-situ studies were done under clean conditions.

Characterization of Oxides and Thin Films

1993 ◽  
Vol 309 ◽  
Author(s):  
Iain D. Baikie ◽  
Gerrit H. Bruggink
Keyword(s):  
Work Function ◽  
Local Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Interface Condition ◽  
Semiconductor Surface ◽  
Kelvin Probe ◽  
Preparation Methods ◽  
Surface And Interface ◽  
Wide Range

AbstractUsing a new, high resolution, microscopic Scanning Kelvin Probe (SKP), work function topographies of metal, semiconductor and metal/semionductor surfaces have been studied in both Ultra-High-Vacuum (UHV) and air environments.The work function is a very sensitive indicator of surface and Interface condition and has been previously utilized to examine preparation methods, surface roughness, adsorption processes, thin film monitoring and residual surface contamination.Extension of the basic method, via Illumination of the semiconductor surface under the tip allows one to probe the local density of states (LDOS). Variations in LDOS can be used to monitor metal contamination, interface traps, bulk contamination, oxide imperfections, etc.Work function topographies generated in this fashion have application in quality control at all stages of the manufacturing process. The Kelvin method of measuring work function is non-contact and non-destructive, utilizing neither high fields nor large currents. It can be applied to a variety of environments ranging from UHV to air and at a wide range of temperatures.

In-situ study of multi-phase indium nanoparticle growth on/into CuPcF4 organic thin film in ultra-high vacuum conditions

2021 ◽  
Vol 546 ◽  
pp. 149136
Author(s):  
O.V. Molodtsova ◽  
I.M. Aristova ◽  
D.V. Potorochin ◽  
I.I. Khodos ◽  
A.N. Chaika ◽  
...  
Keyword(s):  
Thin Film ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Organic Thin Film ◽  
Nanoparticle Growth ◽  
In Situ Study ◽  
Multi Phase

Smart Thin Film TiNi/Pzt Heterostructures

1994 ◽  
Vol 360 ◽  
Author(s):  
Peter G. Mercado ◽  
A.Peter Jardine
Keyword(s):  
Thin Film ◽  
Shape Memory ◽  
Vacuum Chamber ◽  
Sol Gel ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ferroelectric Ceramics ◽  
Active Structures ◽  
Quartz Substrates

AbstractThin film layers of shape memory alloys and ferroelectric ceramics can produce a family of ‘smart’ heterostructures capable of performing both sensing and actuating functions. Important issues in the synthesis of these active structures are the ability to generate the appropriate crystalline phases of each material, while producing defect-free homogeneous high quality films. The compatibility of sol-gel processed Pb(Zr,Ti)O3 (PZT) thin films with thin film shape memory effect TiNi substrates were investigated. Thin film TiNi was deposited on quartz substrates by physical sputter deposition utilizing a TiNi target in a ultra-high vacuum chamber, and followed by in-situ vacuum annealing. PZT was deposited on TiNi by sol-gel and spin coating processes. The ferroelectric tetragonal phase of PZT was obtained by a 600 °C anneal for 5m in air. The heterostructures were nominally defect-free, unlike those obtained through deposition onto bulk TiNi substrates.x

Direct observation of the work function evolution of graphene-two-dimensional metal contacts

2014 ◽  
Vol 2 (38) ◽  
pp. 8042-8046 ◽  
Author(s):  
Songbo Yang ◽  
Peng Zhou ◽  
Lin Chen ◽  
Qingqing Sun ◽  
Pengfei Wang ◽  
...  
Keyword(s):  
Work Function ◽  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Graphene Monolayer ◽  
Two Dimensional ◽  
Metal Contacts ◽  
System P

The work function evolution of a graphene monolayer under two-dimensional metal electrodes was studied by combining in situ metal deposition and ultraviolet photoelectron spectroscopy under an ultra-high vacuum system.

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

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