Auger Electron Spectroscopy Depth Research Articles

Ag/Ai schottky contacts on n-InP

Schottky contacts have been fabricated onn- InP using a Ag/Al/InP configuration where the Ag and Al thicknesses are 1000 and 40-50A, respectively. Diodes fabricated on InP substrates withn ≈ 7 x 1016 cm-3, have effective barrier heights, Obeff, of 0.4 eV and reverse bias leakage current densities of >4 A/cm2 atVr = - 3V. Appropriate heat treating at temperatures between 400–500° C raises barrier heights by as much as 0.25 eV, resulting in Obeff ≈ 0.65 eV and reverse bias leakage current densities less than 0.002 A/cm2. Diode characteristics are found to vary dramatically with different surface preparations prior to metallization; results of x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) depth profiling studies indicate that native oxides which are predominantly InPO4 produce superior contacts and that aluminum first reacts with the native oxide and then migrates through the silver to the free metal surface which results in the dramatic improvements observed upon annealing.

Simultaneous SIMS/AES Measurements for the Characterization of Multilayer Systems

The interface region of silicon dioxide layers deposited on indium phosphide was investigated by simultaneous secondary ion mass spectroscopy (SIMS) and Auger electron spectroscopy (AES) depth profile measurements. The results of such measurements depend strongly on the ion species used for sputtering. With Ar+ primary ions an enhancement of the P- and In-SIMS signals occurs in the mixing zone at the interface. This effect can be explained by an increase of the ionization yield of In and P in the presence of oxygen from the SiO2. The use of O2 + as sputter ions enlarges the phosphorus peak at the interface while the enhancement of the In-signal diminishes. The simultaneously measured AES spectra give clear evidence of oxygen bonded In and P at the interface. Additionally, preferential sputtering of phosphorus occurs. The understanding of these effects which complicate the interpretation of SIMS and AES depth profile measurements of the system SiO2/InP allows us to investigate the silicon dioxide layers and the interface region in order to optimize the SiO2 deposition process, e.g. for surface passivation or MIS structures.

表面粗さのオージェプロファイルへの影響

The effect of surface roughness on depth profile in Auger Electron Spectroscopy (AES) has been experimentally studied. Films of a-Si : H were prepared by the glow discharge decomposition of SiH4 on substrates with various roughness and characterized by AES analysis. In AES depth profiles, the broadening width of a-Si : H/substrate interface increased with enhancing the roughness of the substrate. On the other hand, the decrease in Auger peak to peak intensity of a-Si : H layer is not observed. These results show that the broadening of iprofile is caused not by the sputter induced roughness, but by the surface roughness of the substrate. Consequently the broadening width (ΔW) of the interface is confirmed to be explained by expression as a function of X, such as ΔW=a·exp (b · X), where X is the roughness of substrate, and, a and b are coefficient.

Interface width of anodic native oxide—InSb structures

Using our improved quantitative analysis of Auger electron spectroscopy (AES) depth profiles, we have found a linear relationship between the interface width of plasma- and wet-anodized InSb (111) and the oxide thickness in the range of 15–180 nm. Using a simple etching technique we have been able to ascertain that the effect was inherent to the oxidation process and not a result of the sputtering process. We have developed a theoretical model that explains the linear relationship in terms of field-enhanced diffusion and oxidation reaction. The model is based on our earlier experiments that demonstrated the oxygen diffusion through the oxide to the interface. Application of the model to the results of over 30 different AES depth profiles yields excellent agreement with the experimental observations that show that the interface width is about 0.25 of the total oxide thickness. The results support the thermodynamic model of anodization, indicating that interface formation is the last step of the oxide growth process.

Characterization of Surface Films on an Anodically Polarized Ferritic Stainless Steel

Abstract Anodic polarization measurements were made for SAE Type J409 stainless steel (12% Cr) using deaerated sodium sulfate solutions in which the pH, temperature, and molarity were varied. Electron Spectroscopy for Chemical Analysis (ESCA) and Auger Electron Spectroscopy (AES) surface data were obtained to help explain unusual polarization phenomena, such as the extreme sensitivity to pH of the critical anodic current (ic) and the inverse effect of temperature on ic. AES depth profiles were also used to determine the nature and thickness of oxide and hydroxide films formed at critical locations in the active, passive, and prepassive regions on the anodic polarization curve. Results of surface studies showed that the elemental composition of the films at open circuit and at the primary passive potential are virtually identical to each other for a given system, and that film thickness reaches a maximum just beyond the primary passive potential during anodic polarization. Films that were composed initiall...