• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1699-1705
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• 1989

Nitridation of about 300\ulcornerSiO2 filmss thermally grown on Si was performed in NH3 plasm ambient (0.2-2 torr) at 900\ulcornerC-1100\ulcorner for 15-20 minutes. The peoperties of those films have been investigated by analyzing the AES and the SIMS data, and the results of the I-V and the C-V measurements. At the plasma ambient of less than 1.5 torr pressure, etching of the films have been shown. Above the 1.5 torr pressure, however, SiO2 films were nitrided as SiIxNy. Plasma thermal nitridation of SiO2 by addition of small amount (6%) of CF4 to the NH3 showed higher pile-up N concentration in the surface region of SiOxNy film. The higher the nitridation temperature is and the longer the nitridation time is the larger the dielectric constant is. The plasma thermal nitridation of silicon dioxide on silicon causes the flat-band voltage shift based on the formation of the positive charge. The conduction mechanism for SiOxNy films could be elucidated by Fowler-Nordheim tnneling model. By SIMS analysis, surface of the film nitrided in plasma process has less contamination than that of the film nitrided in open-tube process.

• Journal of Information Display
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• v.1 no.1
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• pp.63-69
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• 2000

In order to improve both the level and the stability of electron emission, Mo and Co silicides were formed from Mo mono-layer and Ti/Co bi-layers on single crystal silicon field emitter arrays (FEAs), respectively. Using the slope of Fowler-Nordheim curve and tip radius measured from scanning electron microscopy (SEM), the effective work function of Mo and Co silicide FEAs were calculated to be 3.13 eV and 2.56 eV, respectively. Compared with silicon field emitters, Mo and Co silicide exhibited 10 and 34 times higher maximum emission current, 10 V and 46 V higher device failure voltage, and 6.1 and 4.8 times lower current fluctuation, respectively. Moreover, the emission currents of the silicide FEAs depending on vacuum level were almost the same in the range of $10^{-9}{\sim}10^{-6}$ torr. This result shows that silicide is robust in terms of anode current degradation due to the absorption of air molecules.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.54-57
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• 2002

In this study, a new programming method, to minimize the generation of Si-SiO$_2$ interface traps of scaled SONOS flash memory as a function of number of program/erase cycles has been proposed. In the proposed programming method, power supply voltage is applied to the gate, forward biased program voltage is applied to the source and the drain, while the substrate is left open, so that the program is achieved by Modified Fowler-Nordheim (MFN) tunneling of electron through the tunnel oxide over source and drain region. For the channel erase, erase voltage is applied to the gate, power supply voltage is applied to the substrate, and the source and drain are open. A single power supply operation of 3 V and a high endurance of 1${\times}$10$\^$6/ prograss/erase cycles can be realized by the proposed programming method. The asymmetric mode in which the program voltage is higher than the erase voltage, is more efficient than symmetric mode in order to minimize the degradation characteristics of scaled SONOS devices because electrical stress applied to the Si-SiO$_2$ interface is reduced by short programming time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.8
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• pp.699-705
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• 2008

Capacitance versus voltage (C-V) characteristics of Ge-nanocrystal (NC)-embedded metal-oxide-semiconductor (MOS) capacitors with $HfO_2$ gate material were investigated in this work. The current versus voltage (I-V) curves obtained from Ge-NC-embedded MOS capacitors fabricated with the $NH_3$ annealed $HfO_2$ gate material reveal the reduction of leakage current, compared with those of MOS capacitors fabricated with the $O_2$ annealed $HfO_2$ gate material. The C-V curves of the Ge-NC-embedded MOS capacitor with $HfO_2$ gate material annealed in $NH_3$ ambient exhibit counterclockwise hysteresis loop of about 3.45 V memory window when bias voltage was varied from -10 to + 10 V. The observed hysteresis loop indicates the presence of charge storages in the Ge NCs caused by the Fowler-Nordheim (F-N) tunneling. In addition, capacitance versus time characteristics of Ge-NC-embedded MOS capacitors with $HfO_2$ gate material were analyzed to investigate their retention property.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.262-263
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• 2008

The Metal-Insulator-Silicon (MIS) capacitors with $SiO_2$ and high-k dielectric were investigated. The high-k dielectrics were obtained by atomic layer deposit (ALD) system. The electrical characteristics were investigated by measuring the current-voltage (I-V) characteristics. The conduction mechanisms were analyzed by using the Fowler-Nordheim (FN) plot and Direct Tunneling (DT) plot. As a result, the MIS capacitors with high-k dielectrics have lower leakage current densities than conventional tunnel-barrier with $SiO_2$ dielectrics.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.56-63
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• 1997

There generally exists a large variation in the thereshold voltages of the flash EEPROM cells after they are erased by using th fowler-nordheim tunneling, thereby getting some cells to be overeased. If the overerased cells are programmed with the conventional one-step programming scheme where an 12-13V pulse with the duration of 100.mu.S is applie don the control gate for the programming, they can suffer from the significant degradation of the reliability of the gate oxide. A two-step programming schem, where an 8/12 V pulse with a duration of 50.mu.S for each voltage is applied on the control gate for the programming, has been studied to solve the problem. The experimental results hav eshown that there is little difference in the programming characteristics between those two schemes, whereas the degradation of the gate oxide due to the programming can be significantly reduced with the two-step programming scheme compared to that with the one-step programming scheme. This is possibly because the positive charge stored in the floating gate of the overerased cells is compensate dwith the electrons injected into the floating gate while the 8V pulse is applied on the control gate, which leaves the overerased cells in the normally erased state after the duration of the 8V pulse.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.2
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• pp.83-88
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• 2003

The reset operation of a CCD image sensor was improved using charge trapping of a MOS structure to realize a loe voltage driving. A DC bias generating circuit was added to the reset structure which sets reference voltage and holds the signal charge to be detected. The generated DC bias is added to the reset pulse to give an optimized voltage margin to the reset operation, and is controlled by adjustment of the threshold voltage of a MOS transistor in the circuit. By the pulse-type stress voltage applied to the gate, the electrons and holes were injected to the gate dielectrics, and the threshold voltage could be adjusted ranging from 0.2V to 5.5V, which is suitable for controlling the incomplete reset operation due to the process variation. The charges trapped in the silicon nitride lead to the positive and negative shift of the threshold voltage, and this phenomenon is explained by Poole-Frenkel conduction and Fowler-Nordheim conduction. A CCD image sensor with $492(H){\;}{\times}{\;}510(V)$ pixels adopting this structure showed complete reset operation with the driving voltage of 3.0V. The resolution chart taken with the image sensor shows no image flow to the illumination of 30 lux, even in the driving voltage of 3.0V.

• Korean Journal of Materials Research
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• v.13 no.10
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• pp.663-667
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• 2003

The effects of paste materials on field emission properties in a carbon nanotube(CNT) cathode were investigated for high-efficient field emission displays. The major components in CNT paste for screen printing were a metallic Ag-paste, a dielectric glass-frit and CNT ink. The emission current from the cathode by an electron tunneling effect increased with an increase in the dielectric material fraction in the CNT paste, which is related to an increase of field enhancement factor in Fowler-Nordheim equation. The surface treatment used, after soft baking of the screen-printed CNT films, greatly affected the decrease in the turn-on field in CNT cathode and the uniformity of emission sites over the entire CNT film area.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.309-312
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• 2002

Triode field emitters with planar-carbon-nanopaticle (CNP) cathodes were successfully fabricated using the conventional photolithography and the hotfilament chemical vapor deposition. Electron emission from a CNP triode emitter with a 12-${\mu}m$-diameter gate hole started at the gate voltage of 45 V, and the anode current reached the level of ${\sim}120$ nA at the gate voltage of 60 V, respectively. For the quantitative analysis of the Fowler-Nordheim (F-N) type emission from a CNP triode emitter, we carried out 2dimensional numerical calculation of electrostatic potential using the finite element method. As it turned out, a radial variation of electric field was very important to account for the emission from a planar emitting layer. By assuming the graphitic work function of 5 eV for CNPs, we were able to extract a consistent set of F-N parameters, together with the radial position of emitting sites.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.860-862
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• 1999

we have grown vertically aligned carbon nanotubes on a large area of Co-Ni codeposited Si substrates by thermal chemical vapor deposition using $C_{2}H_{2}$ gas. The carbon nanotubes grown by the thermal chemical vapor deposition are multi-wall structure, and the wall solace of nanotubes is covered with defective carbons or carbonaceous particles. The carbon nanotubes range from 50 to 120nm in diameter and about $130{\mu}m$ in length at $950^{\circ}C$. The turn-on voltage was about $0.8V/{\mu}m$ with a current density of $0.1{\mu}A/cm^2$ and emission current reveals the Fowler-Nordheim mode.