1,721,003 research outputs found
Effects of design parameters on non-biased optical bistable devices using multiple quantum well nipi-diode structure
No full textWe have studied the effect of design parameters on the performance of non-biased optical bistable (NOB) devices fabricated with non-resonant multiple quantum wells nipi-diode structures. This device made of extremely shallow quantum wells as intrinsic regions allows both a large low-field electroabsorption change and exciton ionization, and consequently, ensures both large electric field swing and strong Light absorption without external bias voltage. By optimizing stack pairs of non-resonant nipi-structures, the performance of the NOB device was significantly enhanced with a large signal contrast ratio, low heat power dissipation, and low drive voltage, while maintaining low switching energy, high signal difference, and layout simplification. (C) 1998 Elsevier Science BN. All rights reserved.This work was supported by the Ministry of Information and Communications, Republic of Korea
PEALD of a ruthenium adhesion layer for copper interconnects
No full textRuthenium thin films were produced by plasma-enhanced atomic layer deposition (PEALD) using an alternating supply of bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)(2)] and NH3 plasma at a deposition temperature of 270 degreesC. The film thickness per cycle was self-limited at 0.038 nm/cycle, which was thinner than the thickness obtained from the conventional ALD using oxygen instead of NH3 plasma. The ruthenium thin film prepared with PEALD had a preferential orientation toward (002), and it was progressively promoted with NH3 plasma power. The PEALD of ruthenium shows a merit in controlling ultrathin film thickness with less than 2 nm more precisely and more easily than the conventional ALD, due to the reduced transient period at the initial film growth stage. Also, ruthenium thin film improved the interfacial adhesion of metallorganic chemical vapor deposited copper to diffusion barrier metals by forming Cu-Ru chemical bonds at the interface without degrading the film resistivity of copper. (C) 2004 The Electrochemical Society.This work was supported by the project of National Research Laboratory (NRL).
The Korea Advanced Institute of Science and Technology assisted in meeting the publication costs of this article
Plasma-enhanced atomic layer deposition of ruthenium thin films
No full textPlasma-enhanced atomic layer deposition (PEALD) of ruthenium thin films was performed using an alternate supply of bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)(2)] and NH3 plasma. NH3 plasma acted as an effective reducing agent for Ru(EtCp)(2). The ruthenium film formed during one deposition cycle was saturated at 0.038 nm/cycle, and its resistivity was 12 muOmega cm. No carbon or nitrogen impurities were incorporated in the film as determined by elastic recoil detection time of flight. The film density was higher than that formed by a conventional ALD, in which oxygen was used. The root-mean-square surface roughness of a 50 nm thick PELAD ruthenium film was 0.7 nm. (C) 2004 The Electrochemical Society.This work was supported by the project of National Research Laboratory ~NRL!.
Korea Advanced Institute of Science and Technology assisted in meeting the publication costs of this article
Plasma-enhanced atomic layer deposition of Ru-TiN thin films for copper diffusion barrier metals
No full textRuthenium-titanium nitride (Ru-TiN) thin films were grown by plasma-enhanced atomic layer deposition (PEALD) at a growth temperature of 200 degrees C. For the Ru - TiN PEALD, Ru and TiN were sequentially deposited to intermix TiN with Ru. The composition of Ru - TiN films was controlled by changing the number of deposition cycles allocated to Ru, while the number of deposition cycles for TiN was fixed to one cycle. The microstructures of Ru - TiN films changed from polycrystalline to amorphous, as the intermixing ratio of Ru increased in the deposited Ru - TiN films. The resistivity of the Ru - TiN film was abruptly increased by adding Ru at the first stage, but after showing a peak resistivity, it decreased with the intermixing ratio of Ru in the films. Especially, the film of Ru-0.67 -(TiN)(0.33) showed an electrical resistivity of 190 mu Omega cm. As a Cu diffusion barrier layer, amorphous Ru - TiN films showed a superior copper diffusion barrier property to TiN or Ru itself, which had a polycrystalline structure. Moreover, Ru - TiN films showed a good adhesion to both chemical vapor deposition copper and an underlayer of SiO2. (C) 2006 The Electrochemical Society.This work was supported by the project of System IC 2010.
Korea Advanced Institute of Science and Technology assisted in meeting the publication costs of this article
Atomic Layer Deposition of Ruthenium Thin Films for Copper Glue Layer
No full textRuthenium thin films were produced by atomic layer deposition (ALD) using an alternating supply of bis(ethylcyclopentadienyl) ruthenium [Ru(EtCp)(2)] and oxygen at a deposition temperature of 270 degreesC. The relative ratio of the Ru(EtCp)(2) adsorbed on the film surface to the oxygen partial pressure in the following oxygen pulse determines whether Ru or RuO2 film was obtained. At the range with higher relative ratio the film was composed of ruthenium, but the film deposited at the lower range was revealed to be ruthenium oxide. In case of the ruthenium thin film, the film thickness per cycle was saturated at 0.15 nm/cycle, and its resistivity was about 15 muOmega cm. The impurities of carbon and oxygen were incorporated into the film with less than 2 atom %. It was also demonstrated that the ruthenium thin films prepared by ALD can be used as an excellent glue layer to improve the interfacial adhesion of metallorganic chemical vapor deposited copper to TiN. Secondary ion mass spectroscopy analysis showed that the ruthenium glue layer suppressed the interfacial contaminants, such as carbon and fluorine, which originated from the metallorganic precursors of copper. (C) 2004 The Electrochemical Society.This work was supported by Samsung Electronics and the projects of System IC 2010 and National Research Laboratory.
Korea Advanced Institute of Science and Technology assisted in meeting the publication costs of this article
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
All-optical oscillator based on the anti-parallel connection of two GaAs/AlGaAs multiple shallow quantum well PINIP diodes
No full textThe authors propose a new scheme for a non-biased all-optical oscillator based on the anti-parallel connection of two GaAs/ AlGaAs multiple shallow-quantum well p-i-n-i-p (PINIP) diodes. Under the illumination of 3mW lasers, the oscillator revealed the electrical and optical oscillations with a frequency of similar to 43.8MHz. The intensity oscillations in the reflected beams from the two diodes showed a phase difference of pi, an on/off reflection change of similar to 22%, and a contrast ratio of similar to 2.This work was supported by the Ministry of Information and Communications, Republic of Korea
Optical and electrical tuning of the frequency in self-oscillating multiple shallow quantum-well diodes
No full textWe have studied photoinduced self-oscillation characteristics in GaAs/AlGaAs multiple shallow quantum-well diodes as a function of bias voltage and laser power. Under the illumination of a laser of wavelength corresponding to the exciton absorption energy, the I-V curve of the diode revealed a large negative differential conductance region where the electrical and optical oscillations were observed in the same phase. The oscillation frequency was widely tuned by either bias voltage or laser power, and this demonstrates a large potential of the device scheme for the electrical and optical signal generators with wide frequency tunability. (C) 1999 American Institute of Physics. [S0003-6951(99)01317-0].This work was supported by the Ministry of Information and Communications, Republic of Korea
Abnormal photocurrent-voltage behavior of GaAs/AlGaAs multiple shallow quantum well p-i-n diodes
No full textWe have observed the abnormal photocurrent-voltage (I-V) behavior in GaAs/AlGaAs multiple shallow quantum wells p-i-n diodes. Under the illumination of a laser, two current plateaus were developed at the negative conductance region of the I-V curve, along with some hystereses depending on the scan direction. At the first plateau, two major oscillations of similar to 120 kHz and similar to 37 MHz were observed with several minor oscillations of frequencies below the latter, while this latter component was uniquely at the other plateau. Analyzing the electrical and the optical oscillations, we explain that one hysteresis at the first plateau was due to the low frequency bias-circuit oscillations, whereas the other at the next plateau was attributed to the intrinsic behavior of the p-i-n diode. (C) 1998 American Institute of Physics.This work was supported by the Ministry of Information and Communications, Republic of Korea
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