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First results obtained from electron beam annealed sequentially implanted Pb+ (29 keV) and Se+ (25 keV) ions into a SiO2 matrix are presented. Key results from Rutherford backscattering spectrometry and transmission electron microscopy investigations are: (1) Pb and Se atoms are found to bond in the SiO2 matrix during implantation, forming into nanoclusters even prior to the annealing step, (2) Pb and Se atoms are both present in the sample after annealing at high temperature (T = 760 °C, t = 45 min) and form into PbSe nanoclusters of varying sizes within the implanted region, and (3) the broader concentration profile of implanted Se creates a number of secondary features throughout the SiO2 film, including voids and hollow shell Se nanoclusters. A sequential ion implantation approach has several advantages: selected areas of nanocrystals can be formed for integrated circuits, the technique is compatible with present silicon processing technology, and the nanocrystals are embedded in an inert matrix – making them highly durable. In addition, a higher concentration of nanocrystals is possible than with conventional glass melt techniques.

Fabrication of nanoscale devices that exploit the rules of quantum mechanics to process information presents formidable technical challenges because of the need to control quantum states at the level of individual atoms, electrons or photons. We have used ion implantation to fabricate devices on the scale of 10 nm that have allowed the development and test of nanocircuitry for the control of charge transport at the level of single electrons. This fabrication method is compatible with the construction of devices that employ counted P dopants in Si by employing the technique of ion beam induced charge (IBIC) in which single 14 keV P ions can be implanted into ultra-pure silicon substrates by monitoring on-substrate detector electrodes. We have used IBIC with a MeV nuclear microprobe to map and measure the charge collection efficiency in the development of the electrode structure and show that 100% charge collection efficiency can be achieved. Prototype devices fabricated by this method have been used to investigate quantum effects in the control and transport of single electrons with potential applications to solid state quantum information processing devices.

In the near future devices which are fabricated from shallow arrays of few and single atoms will exploit quantum mechanical rules to perform useful functions including quantum computation. Fabrication of these devices presents formidable technological challenges. We have developed a single ion implantation system that is capable of verifiable fabrication of single donor devices using 14 keV 31 P ions implanted into ultra-pure, high resistivity silicon substrates based on the technique of Ion Beam Induced Charge (IBIC). A detection system with integrated detector electrodes registers the charge transient from a single ion impact which is used to signal the implantation of an ion into the substrate. We describe here the use of IBIC with MeV ions to study the charge collection efficiency of the detector electrodes. By using three dimensional numerical technology computer-aided design (TCAD) models for the decrease in the IBIC signal as a function of distance from the detector electrode, we can obtain an accurate measurement of the resistivity of the silicon substrate, allowing confirmation of the values specified by the supplier, and providing us with confidence in the numerical models used by TCAD for simulation. This technique has advantages over resistivity measurements by four-point probes because it is spatially resolved, probes through the intact oxide, and can be done without making contact to the device in the area of the probe.

In complex multi-elemental samples it is often necessary to determine the presence of various chemical phases. More complexity arises if it is also necessary to determine the spatial distribution of these phases. Here we present a new technique, based on the elemental maps, for the study of the phase distribution of multi-elemental samples. This technique uses the elemental maps obtained with nuclear microscopy to extract the spatially distributed phase information. We will explain the basic technique of phase correlation mapping, and then provide simulated and experimental results to demonstrate its capability in materials analysis. The simulations show the effect of the beam spatial resolution on the correlation maps and the experimental results show the phase correlation maps of elements in an array of phosphors from a video tube.