Jochen Teichert

Generation and detection of fluorescent color centers in diamond with submicron resolution

Fluorescent color-center patterns have been written on surfaces of synthetic type-Ib diamonds with spatial resolution below 180 nm via irradiation with focused ion and electron beams and subsequent annealing. The patterns are detected and spectroscopically analyzed using confocal optical microscopy. From the spatial extent of the color-center distributions, the activation energy for diffusion of vacancies in diamond is determined as (2.55±0.15) eV. Detailed information about the formation of color centers in diamond is obtained employing the three-dimensional spatial resolution of the confocal microscope combined with spectral resolution. In particular, the distributions of two color centers, ascribed to different charge states of the NV defect in diamond, have been spatially mapped and shown to depend strongly on the irradiation dose.

Dose rate effects in focused ion beam synthesis of cobalt disilicide

The influence of the dwell-time in focused ion beam synthesis has been investigated. Cobalt disilicide layers have been produced by 70 keV Co2+ implantation into silicon and have been investigated by Rutherford backscattering spectroscopy and scanning electron microscopy. At an implantation temperature of about 400u2009°C it is only possible to form continuous CoSi2 layers using sufficiently short pixel dwell-times. This result is explained by an enhanced damage accumulation for longer dwell-times.

Dwell-time related effects in focused ion beam synthesis of cobalt disilicide

The influence of the high current density of a focused ion beam on the ion beam synthesis of CoSi2 layers has been investigated. After 35 keV Co+ or 70 keV Co2+ implantation into a heated Si(111) substrate and subsequent annealing, the layers have been investigated by scanning electron microscopy and Rutherford backscattering spectroscopy (RBS). It is shown that the mode of beam scanning influences the CoSi2 layer formation significantly. At a given substrate temperature, a sufficient low dwell time is required to obtain a continuous layer rather than a laterally disrupted structure. With increasing target temperature, the dwell-time window becomes less restricted. The results are discussed in terms of damaging and dynamic annealing of the silicon crystal. RBS channeling investigations demonstrate that continuous or disrupted CoSi2 layers are formed when the substrate remains crystalline or becomes amorphous, respectively.

Electron emission characteristics of solidified gold alloy liquid metal ion sources

Abstract Solidified liquid metal ion sources (LMISs) operating with Au alloy wetted hair-pin emitters can be used as high-intensity electron point sources for application in the field of ultrahigh vacuum techniques. A nanotip emitter on a solidified LMIS emitter can be formed by quenching during ion emission mode. I–V characteristics and the performance of the electron emitting LMIS are presented.

Single-Crystalline CoSi2 Layer Formation by Focused Ion Beam Synthesis

The effects of accumulated radiation damage which arise from the excessive current density employed during focused ion beam implantation are described. The dwell time during beam scanning significantly influences the focused ion beam synthesis of CoSi2 in Si. At sufficiently low accumulated damage, single-crystalline CoSi2 layers are obtained, similarly to conventional ion implantation. A procedure is described which enables the reduction of radiation damage induced by a focused ion beam to the level of conventional ion implantation. This is of importance for the formation of single-crystalline CoSi2 layers.

Formation of a nano-emitter for electron field emission on a liquid metal ion source tip after solidification of the alloy

Abstract Liquid metal ion sources (LMISs) operating with solidified Au alloys can be used as high-intensity electron point sources. A nano-emitter can be formed by quenching during ion emission mode. The I–V characteristics and the performance of the electron-emitting LMIS are presented.

Evidence for acoustic waves induced by focused ion beams

Acoustic waves induced by an intensity modulated focused ion beam have been measured. The experiments were performed with Ga+ ions of 35 keV at a current of 3 nA and variable chopping frequency up to 10 MHz in a common focused ion beam system. The acoustic signals were detected by means of a piezoelectric sensor with integrated preamplifier. Frequency and position sensitivity of the sensor has been measured by laser excitation. Ion acoustic measurements have been carried out at the resonance frequencies of the sensor. A dependence on the sample material was found. The results show that the ion acoustic effect can be utilized for imaging and material analysis in focused ion beam systems.

DWELL-TIME DEPENDENCE OF THE DEFECT ACCUMULATION IN FOCUSED ION BEAM SYNTHESIS OF COSI2

Abstract Cobalt disilicide microstructures were formed by 70 keV Co2+ focused ion beam implantation into Si(1xa01xa01) at substrate temperatures of about 400°C and a subsequent two step annealing (600°C, 60 min and 1000°C, 30 min in N2). It was found that the CoSi2 layer quality strongly depends on the pixel dwell time and the implantation temperature. Only for properly chosen parameters continuous CoSi2 layers could be obtained. Scanning electron microscopy and Rutherford backscattering/channelling investigations were carried out combined with a special preparation technique for structures which are smaller than the analysing beam. The quality of the CoSi2 layers which is correlated to the damage was investigated as a function of dwell-time (1–250 μs) and target temperature (355–415°C). The results show that the irradiation damage increases with the dwell-time. The Si top layer was amorphized for longer dwell-times although the substrate temperature was always above the critical temperature for amorphization of about 270°C according to the model of Morehead and Crowder. For the high current density of a focused ion beam (1–10 A/cm2) the damage creation rate is higher than the rate of dynamic annealing.

RBS AND CHANNELING ANALYSIS OF COBALT DISILICIDE LAYERS PRODUCED BY FOCUSED ION BEAM IMPLANTATION

Abstract Cobalt disilicide layers were formed by ion beam synthesis using 35 keV Co + focused ion beam (FIB) implantation into silicon. A strong influence of the pixel dwell-time on the layer formation was found. Only for short pixel dwell-times (about 1 μs) closed layers with sufficient quality for device application could be formed. To understand the dwell-time effect the as-implanted samples were examined by Rutherford backscattering (RBS) and channeling analysis. A method is presented which allows quantitative measurements of samples where the implanted areas are smaller than the diameter of the RBS beam. Evidence has been obtained that the silicon crystal damage is less for short dwell-times.

Investigation of the ion acoustic effect during focused ion beam irradiation

Acoustic waves induced by an intensity modulated focused ion beam (FIB) have been measured. The experiments were performed with Ga+ ions of 35 keV at a current of 3 nA and variable chopping frequency up to 10 MHz. The acoustic signals were detected by means of a piezoelectric sensor with integrated pre-amplifier. A dependence on the sample material was found during line scan FIB motion. The results show that the ion-acoustic effect may be utilized for an alternative sample imaging and material analysis in FIB systems.