摘要:

A quantitative surface analysis by Auger‐electron spectroscopy (AES) or x‐ray photoelectron spectroscopy (XPS) requires a series of operations that typically includes instrument setup, specimen positioning, data acquisition, data manipulation, and data analysis. These operations involve a sequence of measurements which are combined and/or compared with other data to yield an analysis. The final result has an estimated uncertainty that reflects the sum of the separate random and systematic errors in the various measurements and sources of data. We identify the major steps in typical analyses and comment on the major sources of error leading to estimates of uncertainty. Systematic errors generally exceed those of a random nature and are associated with the complex morphology of typical specimens, with parameters of instrument performance, and with limitations of current methodology and data. We review general measurement principles for surface analysis, the development of a suitable analytical strategy, and identify and discuss many of the sources of error. The discussion is specific to AES and XPS but many of the issues are relevant to other techniques of surface analysis. Finally, two examples are presented to illustrate the sources and magnitudes of some of the errors and the final uncertainties in some common examples of surface analyses.

ISSN:0734-2101    

DOI:10.1116/1.576956

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

A simple method for converting an analog high‐resolution electron energy loss (HREEL) spectrometer to a digital instrument is described in this paper. Methods of Fourier transform smoothing of the digital data are described and a comparision to RC‐smoothed analog data is made using synthetic analog data. The advantages of digital data acquisition in HREELS compared to analog methods are presented.

ISSN:0734-2101    

DOI:10.1116/1.576957

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

An accel‐mode einzel lens with through‐lens energy analyzer is developed to apply a purely electrostatic optical column in low‐voltage electron beam testers. A purely electrostatic optical column, enabling use of the accel‐mode einzel lens as an objective lens, is also designed. Lens aberration is lowered by reducing focal length. Energy analyzer performance is improved by calculating secondary electron trajectories for the lens. The purely electrostatic optical column provides a 100 nm beam diam and a 0.23 eV energy resolution at beam voltage of 0.5 kV and beam current of 1 nA.

ISSN:0734-2101    

DOI:10.1116/1.576915

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The different kinds of mixed crystal systems for GaAs1–xPxand Ga1–xAlxP have been investigated by x‐ray photoemission spectroscopy (XPS). The core level binding energies of Ga in GaAs1−xPxincrease, whereas those of P in GaAs1−xAlPxP decrease with compositionx, which are analyzed using Pauling’s ionicity and the ionicity scale of Kowalczyketal. For two kinds of mixed crystals, we found that the energies of plasmon loss peaks increase, all major peaks in the valence band shift the band edge, and the top of the valence band recedes linearly with compositionx. The composition variation of the energy gap for mixed crystals are caused basically by the top of the valence band receding.

ISSN:0734-2101    

DOI:10.1116/1.576916

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Poly(methyl methacrylate) (PMMA) was chosen as a model lithographic material to study the effect of A1Kαradiation and the thermal (flood gun) electron flux on polymer surface. The main chemical changes, which can occur in polymers by radiation, are (1) main‐chain scission, (2) cross linking, and (3) volatile product formation and cyclization. The data shows that, although the flood gun electrons do not affect the PMMA surface, the x‐ray radiation causes degradation in molecular weight by main‐chain scission.

ISSN:0734-2101    

DOI:10.1116/1.576917

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The effect of sample rotation on the ion‐induced surface roughening for multilayer Auger samples is described using preliminary scanning electron microscopy. The surface roughness amplitude of Cu/Ag sandwiches bombarded with 1–3 keV Ar+and Xe+ions was found to be dramatically reduced by sample rotation, resulting in a significant improvement in depth resolution, especially for Ar+‐bombarded samples. The sputtered surfaces of rotated samples were characterized by planar crystals developed thereon, forming a striking contrast to the stationary sample surfaces thickly covered with conical microprojections. The mechanism of this two‐dimensional crystal growth is discussed briefly, in terms of surface atom mobility enhanced by ion impact.

ISSN:0734-2101    

DOI:10.1116/1.576918

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Initial results from a hybrid resonance ionization and secondary ionization mass spectrometer (RIMS/SIMS) instrument are presented. Advantages and disadvantages of both techniques are discussed. RIMS performed with pulsed lasers produces ions more efficiently than SIMS, but with a cost of reduced duty cycle. As a result, SIMS may be more sensitive than RIMS in certain instances. RIMS is shown to reduce background, matrix‐based mass interferences by its selective atomic photoionization process. Matrix ions from Si are discriminated against using RIMS in the detection of Co. The RIMS detection limit for Co in Si is determined to be 1×1018cm−3(20 ppm) for depth profiling applications without pulse counting techniques commonly used in SIMS. Improvements in this figure of merit are possible.

ISSN:0734-2101    

DOI:10.1116/1.576919

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The variation of the angle between the incident electron beam and sample surface contributes in two ways to the secondary electron emission from single crystals. These contributions are a monotonically varying background due to the changing number of secondaries produced near the surface, and an oscillatory component previously explained as a bulk effect related to Kikuchi patterns. This work shows that for emission from a Au(111) surface, the background can be described well by a simple model based on the semiempirical theory of Kanaya and Kawakatsu. It also provides additional support for the explanation of the oscillations as a bulk effect by showing that the oscillation amplitude remains essentially unchanged either by surface sputtering or by the deposition of a thin lead layer. The presence of these oscillations requires some care in the use of the secondary electron crystal current as a measure of the thickness of thin metal films.

ISSN:0734-2101    

DOI:10.1116/1.576920

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Operating a metalorganic (MO) bubbler at low pressure allows a high flux of MO reagent to be extracted without resorting to high carrier gas flows. This approach is particularly suitable for the MOMBE (metalorganic molecular beam epitaxy) growth of III–V compounds. Using a ‘‘see‐through’’ water bubbler, we have compared the theory and practice of reduced‐pressure bubbler operation, both with and without a carrier flow. We conclude that the small carrier approach offers a wider flexibility in the choice of reagent flow, and a better stability and day to day repeatability of reagent flow. The reduced pressure operation of triethylgallium (TEGa) and triethylaluminum (TEAl) bubblers is described, in the context of the MOMBE growth of GaAs and AlAs. We show that using the small carrier flow approach, the reagent flow can be accurately controlled and predicted over a wide range.

ISSN:0734-2101    

DOI:10.1116/1.576921

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

We have developed a new method to precisely control the small mass flow of low vapor pressure gases without a carrier gas in gas source molecular beam epitaxy. Group III metalorganic gases (TEA1, TEIn, and TEGa) were controlled by measuring the pressure difference at the flow element and giving feedback to the control valve. The beam pressure of source gases monitored at the growth position in a molecular beam epitaxy growth chamber had good linearity with the pressure difference at both sides of the flow element. The beam pressure was controlled with a maximum deviation of 2% for over 1 h of operation. The response of the beam pressure to changes in flow rate was quick with neither overshoot nor undershoot. The beam pressure could be reduced to 1/5 of its initial value in less than 5 s and then restored in less than 3 s. The source gases could be switched on and off abruptly. The rise time to 90% of the saturated beam pressure was less than 1 s and fall time to 10% of the saturated beam pressure was between 2 and 4 s.

ISSN:0734-2101    

DOI:10.1116/1.576922

出版商:American Vacuum Society    

年代:1990

数据来源: AIP