Ion Microbeam Research Articles

Nuclear reaction microanalysis: A key for the study of uranium dioxide corrosion mechanisms

Deuteron and/or helium-3 ion microbeams have been used to determine the near-surface composition of uranium dioxide leached in a granitic groundwater and particularly the oxygen depth profile. The use of a ΔE− E telescope allows us to exploit both the backscattering part and the nuclear reaction part of the energy spectra so that the uranium depth profile and the surface O/U ratio of the oxide can be infered. Nuclear reaction investigation has been completed with X-ray photoelectron spectroscopy (XPS) measurements in order to derive simple alteration models.

High energy resolution PIXE analysis using focused MeV heavy ion beams

The possibility of chemical state microanalysis using high energy resolution PIXE was investigated using a plane crystal spectrometer installed at a heavy ion microbeam line. The spectrometer has the advantage for the analysis of an X-ray spectrum of simultaneously detecting X-rays over an energy range using position sensitive proportional counter without scanning the crystal. Though the detection efficiency is estimated to be at least four orders of magnitude lower than energy dispersive X-ray spectroscopy (EDS) using a Si(Li) detector, the resolution of the system ( dE E ) is better than 10 −3, because the effect of beam size on system resolution is negligible. Focused 2 MeV proton and 5 MeV Si 3+ ion beams were employed for the analysis of Si Kα X-rays of Si and SiO 2. In both cases, it is possible to detect chemical effects by observing relative intensities of X-ray satellite peaks. However, the use of heavy ions is considered to be more promising because the yields of satellite lines using silicon ion bombardment was much higher than that of protons.

Development of a fast multi-parameter data acquisition system for microbeam analyses

A commercially available Personal Computer (PC)-based multi-parameter data acquisition system has been developed for ion microbeam analyses. The PC is equipped with a recent fast processor, a large volume of memory and a general multi-channel Analogue to Digital Converter (ADC) interface board. When a signal from an X-ray detector (PIXE), from a particle detector (RBS)or from others triggers this ADC for data acquisition. X-Y beam scanning control signals which indicate the beam position are also digitized at the same time. These data are addressed to the 3D matrices in the memory space, that consist of 1024 channels for the energy spectra and 150 × 150 pixels for corresponding the beam scan area. Real time data processing can be done in addition to this data acquisition by the fast processor with the large memory. Simultaneous PIXE and RBS elemental mapping and ion beam induced charge (IBIC) imaging on fine structure diodes have been demonstrated with this system.

Non-ionic surfactant concentration profiles in undamaged and damaged hair fibres determined by scanning ion beam nuclear reaction analysis

Nuclear Reaction Analysis (NRA) was used with a scanning MeV 3He ion microbeam to determine the extent of permeation and segregation of a deuterated non-ionic surfactant (dC12E5) into virgin (undamaged) and alkalinic perm damaged hair fibres. 2-D concentration maps show an accumulation of deuterated surfactant in the cortex and medulla of both the virgin and damaged hair. By normalising to the matrix carbon, surfactant levels in the damaged hair were found to be three times higher than in the undamaged hair. This is the first reported direct spatial evidence of the penetration of surfactant into the centre of hair fibres. Furthermore it is the first application of NRA to this type of complex biological matrix.

Research of Si and GaAs diode structures by Ion Beam Induced Charge (IBIC) collection

A Si pn junction diode and a GaAs Schottky diode were prepared for studying the basic mechanism of charge collection followed by high energy charged particle incidence in order to improve the resistance against single event upset. A 2 μm wide and 20 μm long rectangular Al electrode attached to a circular Al electrode with a 50 μm diameter was made on a 2.5 μm thick epilayer (minority carrier density 2 × 10 15 /cm 3). Both a Schottky electrode of Al (5 μm × 110 μm) and two ohmic electrodes of AuGe Ni (110 μm × 110 μm) were made on a 2 μm thick epilayer (7.3 × 10 15 /cm 3) grown on a semi insulator GaAs substrate ( 1 × 10 7 Ω cm ). The internal device structure was examined by the IBIC (Ion Beam Induced Charge) method using a 2 MeV He + ion microbeam. IBIC images clearly show an Al electrode, the SiO 2, and an epilayer. These results were then used to improve the qualities of the test diodes.

Study of basic mechanisms of semiconductor devices using ion beam induced charge (IBIC) collection

A change of wave form of current transients induced by a single heavy ion was investigated around a pn junction with 8 μm width and 10 μm length as a function of the ion incident position. Three pn junctions were made on a 3 μm thick Si epilayer (1 × 10 16/cm 3) grown on Si substrate and were in a line along an aluminum electrode with 10 μm spacing between the adjacent junctions. The elements of a pn junction array were irradiated with a 1 μm diameter 15 MeV C + heavy ion microbeam spacing steps by 3 μm. At a bias voltage of − 10 V, 148, 91, and 54 fC were collected at the pn junction center, and at 3 μm and 4 μm from the edge of the electrode, respectively. Internal device structure was examined by IBIC (ion beam induced current) method by using a 2 MeV He + ion microbeam. From the IBIC spectrum and the IBIC image, the charge collected from the open space by the diffusion process was observed in addition to the charge collected from the depletion layer of the pn junction.

Verification of three-dimensional charge transport simulations using ion microbeams

Optically targeted, ion microbeams provide a useful means of exposing individual structures within an integrated circuit to ionizing radiation. With this tool, calibrated, low damage, charge collection spectra can be measured from specific circuit structures without preceding ion damage to the structure or surrounding circuitry. This paper presents comparisons of calibrated, low damage, ion microbeam-based charge collection measurements and three-dimensional, charge transport simulations of charge collection for isolated n- and p-channel field effect transistors under conducting and non-conducting bias conditions.

High energy resolution PIXE with high efficiency using the heavy ion microbeam

An X-ray crystal spectrometer using a position sensitive proportional counter combined with tandem microbeam line at Osaka National Research Institute have been developed. This system realizes high energy resolution PIXE analysis using a heavy ion microbeam ( E < 6 MeV) with reasonable detection efficiency. The design of the spectrometer, such as detection geometry, detectable energy range and energy resolution, are described. This system was applied to high energy resolution PIXE analysis of Ti, SUS and Si with 2 MeV proton and 5 MeV Si 3+ focused or collimated beams. The best energy resolution was 2 eV for the Si Kα line.

Use of the α → β quartz transition to monitor the temperature increase produced by a proton microbeam

Ion microbeams induce in certain cases local heating of a sample under investigation, especially in insulators. To obtain experimental values of this temperature increase, we used a quartz sample which presents its own internal thermometer with the α → β transition observed at 573°C. At this temperature, the transition is easily observed from the rapid variation of the bubble size contained in a melted inclusion trapped in the quartz. We measured the temperature increase produced by a 3 MeV proton microbeam. For this purpose, the nuclear microprobe chamber was equipped with a sample heating stage. The decrease of the power injected by the heater element (beam on) required to observe the transition has been interpreted as a local increase of the temperature under microbeam exposure.

A history of ion microbeams

The evolution of ion microbeams is discussed in terms of the developing knowledge and experience of those involved, their interactions and different perspectives and the vagaries of fortune.

Development of high-resolution single-ion PSD using random access memories

Using heavy-ion microbeam, we have examined the feasibility of a Static Random Memory (SRAM) as an in situ Position Sensitive Detector (PSD) with bit-cell size resolution for extremely low current ion beams. It is found that SRAMs are promising candidates for high-resolution PSD to diagnose an extremely low current ion microbeam.

Performance of an acousto-optic Bragg cell under ion microbeam irradiation

An acousto-optic (AO) deflector composed of PbMoO 4 was exposed to 4 MeV protons while operating under Bragg angle conditions. An ion beam in air of 1 mm width was directed normal to the crystal face and laser beam. Between exposures, the approximately 13 mm × 8.5 mm AO deflector was mechanically translated in two dimensions in front of the fixed ion beam. The AO diffraction efficiency was mapped and was observed to change as a function of ion beam location and dose rate. These effects are attributed to the induced change in the temperature distribution of the crystal, which changed the sonic velocity and refractive index. Similar effects were observed when the ion beam was directed at the acoustic transducer.

Recent progress in JAERI single ion hit system

Single ion hit system has been installed in heavy ion microbeam system in JAERI Takasaki for analysis of single event phenomenon in semiconductor devices. The detection and control of a single ion injection to a target have been achieved by combining a beam pulsing system with a gated detection system. The microscopic observation of a track detector hit by a single ion periodically, shows the controls of the hit positions and numbers of incident ions are successful.

Micromachining using deep ion beam lithography

In recent years the process combining deep X-ray lithography with electroforming and micromoulding (i.e. LIGA), has become an important technique for the production of high aspect-ratio microstructures for the fabrication of micro-electromechanical systems (MEMS). The aim of this paper is to investigate the potential of high energy ion microbeams for carrying out similar micromachining, and in particular for overcoming the geometrical restrictions which are inherent in deep x-ray lithography. Using a scanned 2.0 MeV proton beam of approximately 1 micron diameter, we produced latent microstructures in high molecular weight PMMA resist. These resist microstructures were subsequently developed using a multi-component developer which is highly specific in the removal of exposed resist, while leaving unexposed or marginally exposed material unaffected. A suitable range of exposures has been established, and factors affecting the geometrical fidelity of the produced microstructure have been investigated. The relative advantages and limitations of this technique vis à vis deep X-ray lithography are discussed.

Accuracy of beam positioning in TIARA

A beam scanning and target profiling technique that provides precise and easy beam positioning on samples has been established for the light ion and heavy ion microbeam systems in TIARA of JAERI. The beam positioning accuracy in these systems was measured using nuclear track detectors, CR-39's. The beam positioning accuracy and indirect beam positioning technique in the heavy ion microbeam system enabled extremely low current microbeam to hit targeted virgin points in micro-structure semiconductor test samples for study of single event upset (SEU) transient current properties. This paper gives details of the beam scanning and target profiling system, and describes and discusses the experiments by using this system.

Ion beam studies of events typical of soft errors in semiconductor memories

A fast ion microbeam has been used to study phenomena associated with soft errors in semiconductor memories. A spatially small beam with a fast blanking system is used to study both alpha particle and heavy ion strikes. The heavy ion strikes are typical of the recoil from cosmic-ray-generated neutrons. Charge collection and static RAM error-rate experiments are discussed.

Trace element geochemistry of Martian iddingsite in the Lafayette meteorite

The Lafayette meteorite contains abundant iddingsite, a fine‐grained intergrowth of smectite clay, ferrihydrite, and ionic salt minerals. Both the meteorite and iddingsite formed on Mars. Samples of iddingsite, olivine, and augite pyroxene were extracted from Lafayette and analyzed for trace elements by instrumental neutron activation. Our results are comparable to independent analyses by electron and ion microbeam methods. Abundances of most elements in the iddingsite do not covary significantly. The iddingsite is extremely rich in Hg, which is probably terrestrial contamination. For the elements Si, Al, Fe, Mn, Ni, Co, and Zn, the composition of the iddingsite is close to a mixture of ∼50% Lafayette olivine + ∼40% Lafayette siliceous glass + ∼10% water. Concordant behavior among these elements is not compatible with element fractionations between smectite and water, but the hydrous nature and petrographic setting of the iddingsite clearly suggest an aqueous origin. These inferences are both consistent, however, with deposition of the iddingsite originally as a silicate gel, which then crystallized (neoformed) nearly isochemically. The iddingsite contains significantly more magnesium than inched by the model, which may suggest that the altering solutions were rich in Mg2+.

The AUSTRALIS microbeam ion source

The AUSTRALIS (AMS for Ultra Sensitive TRAce eLement and Isotopic Studies) system being developed at the HIAF laboratory is a microbeam AMS system designed for in situ microanalysis of geological samples. The microbeam source was implemented by modifying a HICONEX source, resulting in a versatile source for microbeam as well as high intensity macrobeam operations. The source features a high magnification sample viewing system, enabling live observation of the sputtering process and visual tuning of the primary beam. Microbeam of Cs+ as small as 30 μm in diameter has been obtained in the tests. The secondary ion extraction system features a “screen” electrode that is used to correct the primary beam trajectory affected by the extraction field, in order to return it to the geometric center of the sample. The paper will describe the source, and results of the test of the source and the injector system.

Optimization of an rf ion source for production of a high-energy ion microbeam

A unit has been designed and implemented expressly for the measurement of brightness, energy spread and mass composition of the ion beam extracted from an ion source. This unit has been used for investigation of the main ion optical characteristics of standard and modified rf ion sources. A magnet system (“mirror” type) consisting of permanent magnet and ferrite materials has been used in the modified rf ion source. The capabilities and advantages of this source are shown in this paper.

Application of chemical effects in X-ray spectra for characterization of the high-Tc superconductors

Abstract Chemical effects in X-ray spectra (energy shifts, emission probability changes, satellite formation and peak profile changes) may be used for characterization of the chemical circumstances and chemical bonding of the monitored element in the sample. For that purpose, an investigation of the chemical effects in ion induced X-ray spectra of the high- T c superconductor materials Sr 2 Ln y Ce 0.5 TaCu 2 O 10+ δ ( Ln =Eu,Sm) was carried out using a high resolution crystal X-ray spectrometer. The applicability of the chemical effects for the mapping of the crystal phases in the superconductor sample using an ion microbeam is discussed.