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62 Direct comparison of field-effect and electrochemical doping in regioregular poly(3-hexylthiophene)
Author(s): H. Shimotani (Affiliation: Inst. for Mater. Sci., Tohoku Univ., Kawaguchi, Japan), G. Diguet, Y. Iwasa
Journal: Appl. Phys. Lett. (USA), vol.86, no.2, p.22104-1-3 (10 Jan. 2005)
Publisher: AIP, USA
Language: English
ISSN: 0003-6951, Full text
Document type: Journal article
Abstract: We have measured carrier mobility of regioregular poly(3-hexylthiophene) films by both field-effect and electrochemical doping on identical devices, which allowed us a direct comparison between the two doping processes. The carrier mobility of electrochemical doping at low doping levels was lower than that of field-effect doping by two orders of magnitudes, while that of electrochemical doping steeply increased with doping levels, reaching comparable or higher values than that of field-effect doping. These results are attributable to carrier trapping by the Coulomb potentials of dopant anions at low doping levels, demonstrating a significant difference between field-effect and chemical doping (13 refs.)
Inspec No.: 8247187
63 Evaluation of nickel and molybdenum silicides for dual gate complementary metal-oxide semiconductor application
Author(s): N. Biswas, J. Gurganus, V. Misra (Affiliation: Dept. of Electr. & Comput. Eng., North Carolina State Univ., Raleigh, NC, USA), Yan Yang, S. Stemmer
Journal: Appl. Phys. Lett. (USA), vol.86, no.2, p.22105-1-3 (10 Jan. 2005)
Publisher: AIP, USA
Language: English
ISSN: 0003-6951, Full text
Document type: Journal article
Abstract: Characteristics of NiSi and MoSi via full consumption of undoped silicon layers have been studied. Interaction of nickel (Ni) and molybdenum (Mo) silicides with SiO2 was evaluated in terms of work function and thermal stability. For nickel silicide, the work function values were low for samples annealed at 400°C even after full consumption of silicon. The work function increased with the anneal temperature and stabilized at 600°C to close to midgap values. Dielectric interaction as a result of silicide formation was studied using current-voltage characteristics. Low leakage currents in these stacks indicated minimum dielectric damage due to silicided gates. Silicidation of Mo was found to be incomplete as the capacitance-voltage curves were marked with larger EOT values and negative shifts in the flatband voltages even at 700°C. Auger depth profiling, high resolution transmission electron microscopy (HRTEM) and x-ray diffraction (XRD) were used for material analysis of the silicided gate stacks (14 refs.)
Inspec No.: 8247188
64 Spatially resolved diagnosis of stress-induced breakdown in oxide dots by in situ conducting atomic force microscopy
Author(s): X.N. Xie (Affiliation: Nat. Univ. of Singapore, Singapore), H.J. Chung, C.H. Sow, A.T.S. Wee
Journal: Appl. Phys. Lett. (USA), vol.86, no.2, p.23112-1-3 (10 Jan. 2005)
Publisher: AIP, USA
Language: English
ISSN: 0003-6951, Full text
Document type: Journal article
Abstract: We report an investigation on the stress-induced breakdown (BD) in ultrathin oxide grown by atomic force microscopy (AFM oxide). A conducting atomic force microscopy (c-AFM) technique was employed to stress the AFM oxide and examine its BD behavior. It was found that thermal annealing has a strong impact on the dielectric strength of AFM oxide. The stress-induced trap generation probability, Pt, could be reduced by ~50% after annealing the oxide at elevated temperatures. Such a thermal effect is related to the local structural relaxation and trap state minimization in AFM oxide upon annealing. The spatially resolved current images allow a microscopic diagnosis of the distribution of BD sites: isolated single BD spots and laterally propagated BD areas were observed in an oxide dot. Soft and hard breakdown sites were also distinguished on the current images (18 refs.)
Inspec No.: 8247219
65 Controlled n-type doping of AlN:Si films grown on 6H-SiC(0001) by plasma-assisted molecular beam epitaxy
Author(s): T. Ive, O. Brandt, H. Kostial, K.J. Friedland, L. Daweritz, K.H. Ploog (Affiliation: Paul-Drude-Inst. fur Festkorperelektronik, Berlin, Germany)
Journal: Appl. Phys. Lett. (USA), vol.86, no.2, p.24106-1-3 (10 Jan. 2005)
Publisher: AIP, USA
Language: English
ISSN: 0003-6951, Full text
Document type: Journal article
Abstract: We study the properties of Si-doped AlN films grown on 6H-SiC(0001) by plasma-assisted molecular beam epitaxy. Whereas nominally undoped AlN films are invariably insulating in nature, Si-doped films are found to be semiconducting with an electron concentration up to 7.4×1017 cm-3, and a resistivity approaching 1 Ù cm at room temperature. Even heavy Sidoping (1×1020 cm-3) does not degrade the structural properties of the AlN films. The morphology of these films is characterized by Si-induced step-bunching, but remains smooth with a rms roughness of about 1 nm (26 refs.)
Inspec No.: 8247238
66 Effect of a Ti cap Layer on the diffusion of Co atoms during CoSi 2 reaction
Author(s): A. Alberti (Affiliation: CNR-IMM, Catania, Italy), R. Fronterre, F. La Via, E. Rimini
Journal: Electrochem. Solid-State Lett. (USA), vol.8, no.2, p.G47-50 (Feb. 2005)
Publisher: Electrochem. Soc, USA
Language: English
ISSN: 1099-0062, Full text
Document type: Journal article
Abstract: Silicide formation in thin cobalt/poly-Si layers capped with Ti during annealing in the temperature range between 420 and 510°C was investigated by time-resolved sheet resistance measurements. We found that CoSi2 nucleation is a fast process while Co diffusion through CoSi2 grain boundaries is a slow process. Simulations of the resistance curves vs. time have shown that the pre-exponential factor of cobalt diffusivity is reduced by the presence of Ti contamination at the CoSi2 grain boundaries, as it was shown by energy-filtered transmission electron microscopy analyses, whilst the activation energy does not change with respect to a reference (10 refs.)
Inspec No.: 8249235
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