[en] The composition of HgCdTe oxides grown by anodic oxidation in a standard KOH/ethylene glycol solution has been determined by neutron activation analysis (NAA). This technique is not hindered by the difficulties normally associated with methods using ion beams or electron beams. Neutron activation analysis has the advantage of being quantitative, and also NAA is not affected by the chemical composition of the matrix. The analysis of the KOH/ethylene glycol oxide film by neutron activation yields Hg:Cd:Te ratios of 0.534:0.19:1, in close agreement with Rutherford backscattering spectroscopy analysis. (orig.)

[en] The remote region of deformation in the very light rare earth region has been investigated by observation of the decay of ¹³⁸Eu and ¹³⁶Eu. These nuclei were produced with ⁴⁸Ti beams incident on ⁹²Mo targets and mass separated on-line at the UNISOR facility. Fifteen gamma rays associated with a 12 +- 1 s activity attributed to ¹³⁸Eu decay have been identified and ten of these placed in a decay scheme. The 2+→0+ transition in ¹³⁶Sm has also been identified. These results are compared to IBM2 and cranking model predictions

[en] The C-V electrical characterization of microstructures on a standard probe station is limited by the magnification of the imaging system and the precision of the probe manipulators. To overcome these limitations, we examine the combination of in situ electrical probing and a dual column scanning electron microscope/focused ion beam system. The imaging parameters and probing procedures are carefully chosen to reduce e-beam damage to the metal oxide semiconductor capacitor device under test. Estimation of shunt capacitance is critical when making femtofarad level measurements. C-V measurements of micron size metal-oxide-silicon capacitors are demonstrated

[en] Single-crystal silicon <100> substrates uniformly doped at approx. >12 Ω cm with boron were deposited with ∼800 A of low-pressure chemically vapor deposited W in a hot-quartz-walled (Anicon) system at a deposition temperature of 300 ⁰C. The samples studied include an as-deposited sample and two others which were post-deposition annealed at 600 ⁰C in Ar for 15 min each. X-ray photoelectron spectroscopy (XPS) coupled with an Ar⁺ ion sputter profiling technique was employed to investigate these structures as a function of depth. Particular emphasis was placed on the depth distribution, content, and chemical state of the fluorine present. Rutherford backscattering spectrometry and x-ray diffraction were used to corroborate the XPS data. Results show that, for the as-deposited and 600 ⁰C annealed sample, the maximum concentration of fluorine (0.6--0.8 at. %) is observed, not at the W/Si interface, but rather at the W (H₂ reduction)/W (Si displacement) interface. For the sample annealed at 850 ⁰C, WSi₂ is formed in the overlayer, and the peak in the F profile corresponds to the position of the WSi₂/Si interface. The maximum concentration of fluorine is reduced by approximately 75% to 0.23 at. % in this sample. From the XPS spectra of the F 1s region, the chemical species of fluorine present in these samples have been identified as WF₆, WF₅, and WF₄

[en] Instrumental neutron activation analysis provides the high sensitivity required for detection of dopants and adventitious impurities in polycrystalline silicon, pulled crystals, and processed wafers. Reactor produced isotopes such as ¹⁹⁹Au provide sufficient sensitivity to study gettering mechanisms at levels equivalent to those of adventitious impurities in processed silicon. Detection of neutron-induced alpha particle radiation provides a quantitative basis for determining the depth distribution of B in Si. Each method plays a synergistic role in the chemical, physical, and electrical characterization of semiconductor silicon. (author)

[en] The remote region of deformation in the very light rare earth region has been investigated by observation of the decay of /sup 138/Eu and /sup 136/Eu. These nuclei were produced with /sup 48/Ti beams incident on /sup 92/Mo targets and mass separated on-line at the UNISOR facility. Fifteen gamma rays associated with a 12+-1 s activity attributed to /sup 138/ decay have been identified and ten of these placed in a decay scheme. The 2+→0+ transition in /sup 136/Sm has also been identified. These results are compared to IBM2 and cranking model predictions

[en] Hafnium aluminate (HfAlO) and nitrided hafnium aluminate (HfAlON) dielectrics were sputter deposited on Si (100) substrate. The N₂/(N₂+Ar) flow ratio was varied between 0 and 66.6% in order to vary the nitrogen concentration. The Hf/Al ratio was varied from 0.5 to 1. In situ x-ray photoelectron spectroscopy and electrical measurements were utilized to characterize the as-deposited HfAlO and HfAlON films. The thermal stability studies of the HfAlO and HfAlON thin films after a 1000 deg. C, 10 s argon rapid thermal anneal were performed using grazing incidence x-ray diffraction and backside secondary ion mass spectrometry. Suppression of crystallization and no detectible outdiffusion of hafnium and aluminum into the silicon substrate were seen for HfAlO and HfAlON thin films with a Hf/Al ratio of 0.5

[en] This study reports fabrication and characterization of nanoscale organic light emitting diodes with reduced charge spreading. Nanoimprint lithography is used to make SU-8 nanochannels with ∼90⁰ sidewalls into which N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) and tris-(8-hydroxyquinoline) aluminum (Alq₃) are thermally evaporated, to avoid charge spreading. Micron grating devices are fabricated for comparison. Device characteristics show that performance is retained while scaling down to nanochannels, as no geometry dependent trend is observed. Surface potential microscopy (SPM) measurements reveal an identical periodic difference in surface potential for nanochannel and microscale grating devices. The SPM results, together with cross-sectional scanning electron microscopy observation of the physical separation of nanoscale organic light emitting diodes (OLEDs), indicate electrical separation and isolated light emission from nanoscale confined OLEDs with minimized charge spreading.

[en] We investigated the impact of doping group IIIA elements (Al, Ga, In and Tl) on the electronic structure and stability of PbTe by first principles calculations. The impurity-induced defect level changes as a function of the charge state of the impurity. We find that Al and In prefer to act as donors while Ga and Tl tend to act as acceptors in PbTe. Our analysis supports the 'impurity level' model where an impurity-induced localized state overlaps either the conduction band or valence band of PbTe, but our results do not agree with 'mix-valence' (i.e. 2In²⁺ → In⁺ + In³⁺) or 'auto-compensation' (i.e. 2In⁰ → In⁺ + In^-) models. Our calculations suggest that Tl and In are suitable dopants for improving the thermoelectric efficiency through enhancing the Seebeck coefficient for p- and n-type PbTe, respectively.

[en] The University of North Texas Ion Beam Modification and Analysis Laboratory consists of three accelerators. These are: a 200 kV, 10 MA Cockcroft-Walton, a 2.5 MV single-ended Van de Graaff machine and a newly installed National Electrostatics Corporation Model 9-SDH-2, 3 MV tandem. The tandem accelerator was received in November of 1987 and acceptance tests were completed in December of 1987. The tandem - and the 2.5 MV Van de Graaff - are now both installed in a new 7000 ft² laboratory in the physics building. The tandem which will be used for many of the activities in the laboratory was purchased with a rf charge exchange (Alphatross) source and a SNICS-type cesium ion sputter source. Each of these sources injects through a 30⁰ magnet into a 90⁰ analysis magnet and then into the tandem accelerator. This configuration gives the high mass resolution which is needed for the AMS system. A table will be shown that overviews the analyzed beams that have been obtained to date with the tandem accelerator. A summary of the beam lines that are being constructed for all the activities of the laboratory will also be given. These include: accelerator mass spectrometry (AMS), nuclear reaction analysis (NRA), Rutherford backscattering and channeling (RBSandC), particle-induced X-ray emission (PIXE), high-energy ion implantation (HEII) and atomic collision physics. (orig.)