Rutherford Backscattering Spectrometry Studies Research Articles

High-resolution Rutherford backscattering spectrometry study on process dependent elemental depth profile change of hafnium silicate on silicon

Process characterization of HfSiO(N)/SiO(N) films was performed by nondestructive elemental depth profile analysis using high-resolution Rutherford backscattering spectrometry. As-grown atomic layer deposition HfSiO film (2 nm) was found not to be uniform but to have a gradient near the top surface with Si concentration higher than the bulk. Regardless of native oxide removal, HfSiO grown on HF-last Si results in an almost identical interfacial SiOx thickness with that of HfSiO grown on chemical oxide. Dependence of interfacial layer on oxygen transport behavior during high-temperature annealing was also investigated. Whereas only the upward oxygen outdiffusion from the HfSiO layer was observed for the films deposited on HF-last Si and SiON, downward oxygen transport to the bottom interfacial layer was also observed when HfSiO film was deposited on chemical oxide. This result indicates that the bonding properties of chemical oxide are different from those of SiO2 and that chemical oxide can accommodate oxygen ions. Finally, thermal stability of nitrogen in HfSiO introduced by NH3 annealing and plasma nitridation was compared. Nitrogen desorption by spike anneal was only observed for HfSiON film with nitrogen introduced by plasma nitridation process.

Low energy oxygen implantation induced improved crystallinity and optical properties of surface modified ZnO single crystals

We report on the low energy oxygen implantation induced improvement in crystallinity and optical properties of surface modified ZnO single crystals. Undoped ZnO (0 0 0 1) single crystal wafers are implanted with 100 keV oxygen ions at a dose of 5 × 10 13 and 5 × 10 14 cm −2 and subsequently annealed at 500 and 600 °C in oxygen ambient. The as-implanted and annealed ZnO wafers are studied by Rutherford back scattering spectrometry (RBS), channeling, Raman, photoluminescence (PL), and Fourier transform infrared spectroscopy (FTIR). Channeling studies show a relatively high χ min (>20%) in the virgin ZnO wafer. After implantation and two-step annealing, RBS studies show improved crystallinity. Raman line width analysis for the E 2 h i g h mode indicates reduction in strain in the annealed samples as compared to the virgin ZnO wafer. As-implanted samples show drastic quenching of the near band-edge (NBE) PL band due to defects created by the implantation. However, after two-step annealing, the low-dose implanted sample show a five-fold increase in intensity ratio of NBE band (376 nm) to defect related broad band (∼530 nm) at room temperature. Implantation induced changes in the composition and improved crystallinity in the near surface region is accounted for the major improvement in the PL emission.

Pt redistribution during Ni(Pt) silicide formation

We report on a real-time Rutherford backscattering spectrometry study of the erratic redistribution of Pt during Ni silicide formation in a solid phase reaction. The inhomogeneous Pt redistribution in Ni(Pt)Si films is a consequence of the low solubility of Pt in Ni2Si compared to NiSi and the limited mobility of Pt in NiSi. Pt further acts as a diffusion barrier and resides in the Ni2Si grain boundaries, significantly slowing down the Ni2Si and NiSi growth kinetics. Moreover, the observed incorporation of a large amount of Pt in the NiSi seeds indicates that Pt plays a major role in selecting the crystallographic orientation of these seeds and thus in the texture of the resulting Ni1−xPtxSi film.

Comparison of ion-induced damage formation in and MgO

Ion-beam induced effects in Ar and Xe implanted <110> and <100> MgO are studied at 15K using Rutherford backscattering spectrometry (RBS). At very low ion fluences the concentration of defects is only determined by the energy density deposited in nuclear processes. Point defects and clusters of point defects are produced with an efficiency of 0.5 independent of ion species, ion energy and crystal orientation. At higher fluences defect annealing and defect rearrangement form a complex defect structure being connected with a variation of the backscattering yield with the crystal axes. A possible interpretation of the energy dependent RBS studies is that at high fluences the implanted layer consists of a mixture of different kinds of defects containing point defects, dislocations and misaligned regions with the misaligned regions dominating in a near-surface layer. The rearrangement of the defects suggests the mobility of some kind of defects at 15K.

Effect of Rb and Cs doping on superconducting properties ofMgB2 thin films

A Rutherford backscattering spectrometry (RBS) study has found thatconcentrations up to 7 at.% of Rb and Cs can be introduced to a depth of∼700 Å inMgB2 thin films by annealing in quartz ampoules containing the elemental alkali metals at<350 °C. No significant change in transition temperature(Tc) (determined resistively) was observed, in contrast to an earlier report of very highTcs (>50 K) from susceptibilitymeasurements on MgB2 powders. The lack of a significant change inTc and intra-granular carrier scattering suggests that Rb and Cs diffuse into the film, but do not enterthe grains. Instead, the observed changes in the electrical properties, including a significant drop inJc and anincrease in Δρ(ρ300−ρ40), arise from a decrease in inter-granular connectivity due to segregation of the heavyalkaline metals and other impurities (i.e. C and O) introduced into the grain boundaryregions during the anneals.

Heterostructure and Compositional Depth Profile of Low-Temperature Processed Lead Titanate-Based Ferroelectric Thin Films Prepared by Photochemical Solution Deposition

The heterostructure and compositional depth profile of low-temperature processed (Pb0.76Ca0.24)TiO3 (PCT24) ferroelectric thin films have been studied in the present work. The films were prepared by ultraviolet (UV) sol–gel photoannealing (also called photochemical solution deposition, PCSD) onto platinized silicon substrates and crystallized at 450 °C in air and oxygen atmospheres. Despite using such a low temperature, analysis carried out by X-ray photoelectron spectroscopy (XPS) revealed the total lack of organic rests within the bulk film. Complementary information about the heterostructure of the films was also obtained by Rutherford backscattering spectroscopy (RBS). Both analytical techniques detected the presence of a lead gradient in the films, together with small fluctuations on the concentration of this element along the bulk film. The RBS study also showed that the films of this work develop a PtxPb interface between the ferroelectric layer and the Pt bottom electrode. The thickness of this in...

Structural and compositional analysis of strain relaxed InGaAs/InP multi quantum wells

The structural and compositional analysis of strain relaxed InGaAs/InP multi quantum wells (MQWs) have been carried out using high resolution X-ray diffraction (HRXRD), Raman spectroscopy (RS) and Rutherford backscattering spectrometry (RBS). The surface morphology has been investigated by atomic force microscopy (AFM). No satellite peaks have been observed in the symmetrical X-ray scans indicating strong strain relaxation, highly mixed InGaAs/InP interfaces and no multilayer characteristics. This limits the structural as well as compositional analysis. Dynamical scattering theory based simulation package has been used to simulate the respective spectra and compared. The RS study shows huge Raleigh scattering induced background resulting low intense phonon modes. In spite of the background we could observe the GaAs and InAs type phonon modes which have been used for the analysis. The RBS studies also indicate the mixed InGaAs/InP interfaces with preferential GaAs and InP precipitation/segregation and the results are discussed in detail comparing with other complementary techniques. Also, AFM analysis has been utilized to obtain the composition in comparison with related literature.

RBS and micro-PIXE study of I and Cs Heterogeneous Retention on Concrete

AbstractA combination of two nuclear ion beam techniques, Rutherford Backscattering Spectrometry (RBS) and micro-Particle Induced X-Ray Emission (uPIXE) was tested to evaluate both diffusion profiles and radionuclide spatial distribution of radionuclides (RN) onto cement-based materials. The methodology was tested on a Spanish reference backfill concrete, used as engineering barrier in low-level radioactive waste repositories, using two elements (Cs and I) with different sorption behaviour onto the cement. The applicability and limitations of the selected methodology is discussed for both elements.

FTIR and RBS study of ion-beam synthesized buried silicon oxide layers

Single crystal silicon samples were implanted at 140keV by oxygen (16O+) ion beam to fluence levels of 1.0×1017, 2.5×1017 and 5.0×1017cm−2 to synthesize buried silicon oxide insulating layers by SIMOX (separation by implanted oxygen) process at room temperature and at high temperature (325°C). The structure and composition of the ion-beam synthesized buried silicon oxide layers were investigated by Fourier transform infrared (FTIR) and Rutherford backscattering spectroscopy (RBS) techniques. The FTIR spectra of implanted samples reveal absorption in the wavenumber range 1250–750cm−1 corresponding to the stretching vibration of Si–O bonds indicating the formation of silicon oxide. The integrated absorption band intensity is found to increase with increase in the ion fluence. The absorption peak was rather board for 325°C implanted sample. The FTIR studies show that the structures of ion-beam synthesized buried oxide layers are strongly dependent on total ion fluence. The RBS measurements show that the thickness of the buried oxide layer increases with increase in the oxygen fluence. However, the thickness of the top silicon layer was found to decrease with increase in the ion fluence. The total oxygen fluence estimated from the RBS data is found to be in good agreement with the implanted oxygen fluence. The high temperature implantation leads to increase in the concentration of the oxide formation compared to room temperature implantation.

Cyclic voltammetry and RBS study of paint components

Heavy metals and metalloid ions are found in environmental matrices. The most toxic are lead, cadmium and mercury. These three heavy metals have no biological function and are toxic at all concentrations. Lead is one of the most insidious heavy metals and is introduced into the environment by many different means. It persists in both urban and rural settings, being found in paint chips, pottery, crystal and pharmaceutical and nutritional products. The analysis of heavy elements such as lead in soil is of particular importance [W.T. Sturges, R.M. Harrison, Sci. Total Environ. 44 (3) (1985) 225; M.L. Lepow, L. Bruckman, M. Gillette, S. Markowitz, R. Robino, J. Kapish, Environ. Res. 10 (3) (1975) 415; A.E. Daniels, J.R. Kominsky, P.J. Clark, J. Hazard. Mater. B 87 (2001) 117; G. Hutter, D. Moshman, J. Hazard. Mater. 40 (1995) 1]. In preparing the methods for lead detection in paint, we have used Rutherford backscattering spectrometry (RBS) in order to study the type and amount of heavy metal content in paint samples collected at various sites in the historic campus at A&M University (AAMU). We will show the results of our study with emphasis on comparison of what we learned about presence of lead in paints using our ion beam methods compared with the analysis of lead in paints using cyclic voltammetry.

RBS study of epitaxially grown thin films of the double perovskite La2NiMnO6

Epitaxial thin films of La2NiMnO6, a ferromagnetic semiconductor, have been fabricated on different substrates by pulsed laser deposition (PLD) [H. Guo, J. Burgess, S. Street, A. Gupta, T.G. Calvarese, M.A. Subramanian, Appl. Phys. Lett. 89 (2006) 0225509]. X-ray diffraction and Raman scattering observations show that the films are single crystalline and have an orthorhombic structure. Rutherford backscattering spectrometry (RBS) measurements were done on four different samples using 2.1MeV He+ ions. We used RUMP simulation on the RBS data to extract information about the thickness and stoichiometry of the layers. In this paper, we are discussing the differences of the various films investigated.

Structural and Electrical Properties of Epitaxial Nb-Doped SrTiO3 Film Deposited on Si ( 100 ) Substrate

The structural and electrical properties of Nb-doped heteroepitaxial structure prepared by a pulsed laser deposition system were characterized. Using X-ray diffraction analysis and transmission electron microscopy, it was confirmed that the Nb-doped and films on silicon were epitaxially grown. Based on a Rutherford backscattering spectroscopy study, a relatively high density of defects such as oxygen vacancies were observed in the film. The structure exhibits rectifying current-voltage (I-V) characteristics, and a large hysteresis in the I-V characteristics and high resistance ratio under voltage pulse were observed.

Formation and growth of embedded indium nanoclusters by In2+ implantation in silica

Indium nanoclusters are synthesized in an amorphous silica matrix using an ion-implantation technique. Indium ions (In2+) with energy of 890 keV are implanted on silica to fluences in the range of 3×1016–3×1017 cm-2. The formation of indium nanoclusters is confirmed by optical absorption spectrometry and glancing incidence X-ray diffraction studies. A low frequency Raman scattering technique is used to study the growth of embedded indium nanoclusters in the silica matrix as a function of fluence and post-implantation annealing duration. Rutherford backscattering spectrometry studies show the surface segregation of implanted indium. Photoluminescence studies indicate the formation of a small quantity of indium oxide phase in the ion-implanted samples.

Structural and Electrochemical Properties of ZrO2·Hx Thin Films Deposited by Reactive Sputtering in Hydrogen Atmosphere as Solid Electrolytes

The feasibility of applying ZrO2·Hx thin films as solid electrolytes in solid-state ionic energy systems, such as solid oxide fuel cells and supercapacitors was studied. ZrO2·Hx thin films were deposited on Pt/Ti/SiO2/Si substrates by radio-frequency reactive sputtering with various hydrogen volume fractions in reactive gas. With a variation in hydrogen volume fraction, the surface roughness of the as-deposited films increased. In addition, the structure of the as-deposited films grew in the [111] direction with an increase in hydrogen volume fraction. By Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) studies, the Zr/O ratio and hydrogen distribution were evaluated. On the basis of a sample structure of Pt/ZrO2·Hx/Pt/Ti/SiO2/Si for measuring an electrochemical property, an impedance measurement conducted at room temperature revealed an ionic conductivity of 1.67 ×10-6 S/cm, suggesting that ZrO2·Hx thin films can possibly be used as solid oxide thin film electrolytes in all solid-state ionics power devices requiring a hydrogen conducting electrolyte.

RBS, PIXE and NDP study of erbium incorporation into glass surface for photonics applications

This paper reports on the fabrication and the characterisation of successful erbium in-diffusion into silicate glass surface for potential use in photonics active structures through ion beam analytical methods. The erbium doping occurred by ion exchange of erbium ions from a molten source for lithium ions from the specially designed glass substrates. Composition of the optical layers was studied by ion beam analytical techniques: RBS (Rutherford backscattering spectroscopy) characterized depth distribution of the incorporated Er3+ ions and PIXE (particle induced X-ray emission spectroscopy) gave information on the total amount of erbium incorporated in the samples. The NDP (neutron depth profiling) method was used to evaluate changes in distribution of Li+ ions in the surfaces of the fabricated samples. We observed shallow Er profiles that were accompanied by more mobile Cs+, Rb+ ions incorporated in the much deeper layer as compared to the Er. The Li concentration in the glass substrate occurs as the most important parameter for Er diffusion into the glass substrate.

RBS and AFM study of Ag and Au diffusion into PET foils influenced by plasma treatment

AbstractMetallization of polymers is essential for their application in microelectronic elements and photonics devices. We performed a study of the diffusion of Ag and Au atoms in polyethyleneterephtalate (PET). Thin metal layers were deposited using the diode‐sputtering technique on polymer foils at room temperature. Simultaneous post‐deposition annealing and plasma treatment was used to induce metal/polymer intermixing. Concentration profiles of diffused metals were determined by Rutherford backscattering spectrometry (RBS) and diffusion coefficients were extracted. The influence of the plasma treatment on the surface morphology was studied using atomic force microscopy (AFM). Ag atoms exhibit deeper penetration into polymer structures after Ar plasma treatment than after Ar + O2 plasma treatment. AFM measurements show more significant changes of surface roughness (increased roughness and porosity) of Ag on PET surfaces caused by the Ar + O2 plasma treatment compared to Au surfaces. In the case of very rough surfaces, a decrease of metal diffusivity is observed probably owing to a reduction of surface concentration. The metal mobility is strongly influenced by temperature, which is increased either by direct heating of the sample holder or indirectly by plasma discharge. Copyright © 2006 John Wiley &amp; Sons, Ltd.

Structural, optical and compositional studies of stepwise flash evaporated CuIn 3Te 5 films

CuIn 3Te 5 films were grown by stepwise flash evaporation from powder CuIn 3Te 5 source. X-ray diffraction and particle induced X-ray emission analyses confirmed the phase purity and compositional homogeneity of the source material. Transmission electron microscopy studies showed that CuIn 3Te 5 films are single-phase and polycrystalline in nature. Rutherford backscattering spectrometry studies revealed that the films are near stoichiometric. Optical transmittance analysis yielded a band gap of ∼1.03 ± 0.02 eV for CuIn 3Te 5 films, which is in close agreement with the value reported for bulk CuIn 3Te 5.

RBS and NRA analyses of lithium inserted amorphous Li 1+ xNiVO 4 films

rf-Magnetron sputtered LiNiVO 4 thin film was used as a negative electrode for lithium microbatteries applications. Their film composition and thickness were analyzed by Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA) technique by using 4He +, 7Li(p α) 4He reaction respectively. The structure, surface roughness and homogeneity of these films have been investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and auger electron spectroscopy (AES) techniques. The amount of lithium inserted into the LiNiVO 4 films was analyzed by RBS and NRA studies. The results are comparable to those obtained from the electro-analytical technique (galvanostatic method), indicating that ion beam techniques are complementary tools for the analysis of lithium metal oxide thin films.

Transmission electron microscopy and Rutherford backscattering spectrometry studies of Ag2Te films formed from Ag‐Te thin film couples

AbstractFormation of Ag2Te thin films from room temperature (300 K) solid state reaction of Ag and Te thin film couples is investigated. Rutherford Backscattering Spectrometry (RBS) studies confirmed the complete miscibility of the couples and the stoichiometry of the resulting Ag2Te. Structural analysis by Transmission Electron Microscopy (TEM) showed a fine‐grained structure with monoclinic and orthorhombic phases. Annealing at high temperatures resulted in the growth of giant crystallites with monoclinic phase at random sites. (© 2005 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

RBS study of annealing effects in passivated mercury cadmium telluride

Changes in composition in passivated mercury cadmium telluride (Hg1–xCdxTe or MCT) due to annealing have been investigated using Rutherford backscattering spectroscopy (RBS). Different passivated structures such as anodic oxide/MCT, CdTe/MCT and ZnS/MCT annealed at 80 °C in 10−6 Torr (parameters used during device packaging) have been studied and compared with the as-deposited samples. It is found that in as-deposited samples of anodic oxide/MCT and ZnS/MCT, the interface between the passivating layer and the MCT substrate is very sharp and composition of the capping layer remains constant throughout. Composition of the anodic oxide layer is estimated to be Hg:Te:Cd:O::0.4:1:0.25:3.35 while that of ZnS is Zn:S::0.9:1.1. In an annealed anodic oxide/MCT sample, the composition of the upper layer is different from that in the as-deposited sample and the interface is comparatively wider, while in the annealed ZnS/MCT sample the thickness of the interfacial region is found to be more than 50 nm and the composition of the remaining ZnS layer remains unaltered. The composition of the CdTe layer in both cases (as-deposited and annealed) is Cd:Te::1:1 and the interface thickness of the as-deposited sample is found to be ∼35 nm; which on annealing, increases to ∼50 nm.