• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.156-161
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• 2017

This work presents a novel structure for junction-less tunneling field effect transistor (JL-TFET) with a floating gate over the source region. Introduction of floating gate instead of fixed metal gate removes the limitation of fabrication process suitability. The proposed device is based on a heavily n-type-doped Si-channel junction-less field effect transistor (JLFET). A floating gate over source region and a control-gate with optimized metal work-function over channel region is used to make device work like a tunnel field effect transistor (TFET). The proposed device has exhibited excellent ID-VGS characteristics, ION/IOFF ratio, a point subthreshold slope (SS), and average SS for optimized device parameters. Electron charge stored in floating gate, isolation oxide layer and body doping concentration are optimized. The proposed JL-TFET can be a promising candidate for switching performances.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.120-121
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• 2007

Nano-floating gate memory (NFGM) devices were fabricated by using the low temperature poly-Si thin films crystallized by ELA and the $In_2O_3$ nano-particles embedded in polyimide layers as charge storage. Memory effect due to the charging effects of $In_2O_3$ nano-particles in polyimide layer was observed from the TFT NFGM. The post-annealing in 3% diluted hydrogen $(H_2/N_2)$ ambient improved the retention characteristics of $In_2O_3$ nano-particles embedded poly-Si TFT NFGM by reducing the interfacial states as well as grain boundary trapping states.

• Journal of IKEEE
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• v.23 no.1
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• pp.193-199
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• 2019

In this study, we have proposed a floating metal guard ring structure based on TCAD simulation in order to enhance the breakdown voltage characteristics of gallium oxide ($Ga_2O_3$) vertical high voltage switching Schottky barrier diode. Unlike conventional guard ring structures, the floating metal guard rings do not require an ion implantation process. The locally enhanced high electric field at the anode corner was successfully suppressed by the metal guard rings, resulting in breakdown voltage enhancement. The number of guard rings and their width and spacing were varied for structural optimization during which the current-voltage characteristics and internal electric field and potential distributions were carefully investigated. For an n-type drift layer with a doping concentration of $5{\times}10^{16}cm^{-3}$ and a thickness of $5{\mu}m$, the optimum guard ring structure had 5 guard rings with an individual ring width of $1.5{\mu}m$ and a spacing of $0.2{\mu}m$ between rings. The breakdown voltage was increased from 940 V to 2000 V without degradation of on-resistance by employing the optimum guard ring structure. The proposed floating metal guard ring structure can improve the device performance without requiring an additional fabrication step.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.4
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• pp.222-228
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• 2015

Power MOSFETs (metal oxide semiconductor field effect transistor) operate as energy control semiconductor switches. In order to reduce energy loss of the device, it is essential to increase its conductance. However, a trade-off relationship between the breakdown voltage and conductance of the device have been the critical difficulty to improve. In this paper, theoretical analysis of electrical benefits on single floating island power MOSFET is proposed. By the method, the optimization point has set defining the doping limit under single floating island structure. The numerical multiple 2.22 was obtained which indicates the doping limit of the original device, improving its ON state voltage drop by 45%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.605-610
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• 2010

The devices based on electrically erasable programmable read-only memory (EEPROM) structure are proposed for the detection of external electric charges. A large size charge contact window (CCW) extended from the floating gate is employed to immobilize external charges, and a control gate with stacked metal-insulator-metal (MIM) capacitor is adapted for a standard single polysilicon CMOS process. When positive voltage is applied to the capacitor of CCW of an n-channel EEPROM, the drain current increases due to the negative shift of its threshold voltage. Also when a pre-charged external capacitor is directly connected to the floating gate metal of CCW, the positive charges of the external capacitor make the drain current increase for n-channel, whereas the negative charges cause it to decrease. For an p-channel, however, the opposite behaviors are observed by the external voltage and charges. With the attachment of external charges to the CCW of EEPROM inverter, the characteristic inverter voltage behavior shifts from the reference curve dependent on external charge polarity. Therefore, we have demonstrated that the EEPROM inverter is capable of detecting external immobilized charges on the floating gate. and these devices are applicable to sensing the pH's or biomolecular reactions.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.20.1-20.1
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• 2011

The nano-sized quantum structure has been an attractive candidate for investigations of the fundamental physical properties and potential applications of next-generation electronic devices. Metal nano-particles form deep quantum wells between control and tunnel oxides due to a difference in work functions. The charge storage capacity of nanoparticles has led to their use in the development of nano-floating gate memory (NFGM) devices. When compared with conventional floating gate memory devices, NFGM devices offer a number of advantages that have attracted a great deal of attention: a greater inherent scalability, better endurance, a faster write/erase speed, and more processes that are compatible with conventional silicon processes. To improve the performance of NFGM, metal nanocrystals such as Au, Ag, Ni Pt, and W have been proposed due to superior density, a strong coupling with the conduction channel, a wide range of work function selectivity, and a small energy perturbation. In the present study, bismuth metal nanocrystals were self-assembled within high-k $Bi_2Mg_{2/3}Nb_{4/3}O_7$ (BMN) films grown at room temperature in Ar ambient via radio-frequency magnetron sputtering. The work function of the bismuth metal nanocrystals (4.34 eV) was important for nanocrystal-based nonvolatile memory (NVM) applications. If transparent NFGM devices can be integrated with transparent solar cells, non-volatile memory fields will open a new platform for flexible electron devices.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.1
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• pp.21-26
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• 2008

We fabricated nano-particles of ZnO, $In_2O_3$ and $SnO_2$ by using the chemical reaction between metal thin films and polyamic acid. The average size and density of these ZnO, $In_2O_3$ and $SnO_2$ nano-particles was approximately 10, 7, and 15 nm, and $2{\times}10^{11},\;6{\times}10^{11},\;2.4{\times}10^{11}cm^{-2}$, respectively. Then, we fabricated nano-floating gate memory (NFGM) devices with ZnO and $In_2O_3$ nano-particles embedded in the devices' polyimide dielectrics and silicon dioxide layers as control and tunnel oxides, respectively. We measured the current-voltage characteristics, endurance properties and retention times of the memory devices using a semiconductor parameter analyzer. In the $In_2O_3$ NFGM, the threshold voltage shift (${\Delta}V_T$) was approximately 5 V at the initial state of programming and erasing operations. However, the memory window rapidly decreased after 1000 s from 5 to 1.5 V. The ${\Delta}V_T$ of the NFGM containing ZnO was approximately 2 V at the initial state, but the memory window decreased after 1000 s from 2 to 0.4 V. These results mean that metal-oxide nano-particles have feasibility to apply NFGM devices.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.469-471
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• 1995

This paper describes the effect of floating metallic object on do flashover characteristics in all gap producing unipolar ion flow field. Needle-to-plane electrodes of 120mm in gap length were used as the main gap electrode and the tested metallic objects were spheres with the radius of 2,10 and 15mm or needles from 5 to 40mm long. The characteristics of flashover voltage vs. location of the floating object are different completely with the shape of the floating metal and polarity of the applied voltage.

• Korean Journal of Crystallography
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• v.3 no.2
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• pp.72-84
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• 1992

The investigation has been carried out for purification, single crystal growth mechanism and convective phenomena in EBFZM of Nb metal. It is found that the EBFZM refined effectively oxygen and nitrogen, the interstitial impurities in Nb, but carbon was increased slightly by backstream of diffusion pump oil. The mechanism of single crystal growth associated with the second recrystallieation in Nb was suggested from the relationship between texture of starting materials and the crystal growth in EBFZM. It was observed from the investigation of convection phenomena in molten zone that the Marangoni convection was dominant in molten zone, which caused the striation in Nb and increased the purification effect of oxygen and nitrogen.

• Journal of Korea Foundry Society
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• v.42 no.1
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• pp.61-66
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• 2022

Hydraulic units are important components of agricultural and construction machinery, and thus require high-quality castings. However, gas defects occurring inside the sand cores of the castings due to the resin used is a problem. This study therefore aimed to develop a casting simulation method that can clarify the gas defect positions. Gas defects are thought to be caused by gas generated after the molten metal fills up the mold cavity. The gas constant is the most effective factor for simulating this gas generated from sand cores. It is calculated by gas generating temperature and analysis of composition in the inert gas atmosphere modified according to the mold filling conditions of molten metal. It is assumed that gases generated from the inside of castings remain if the following formula is established. [Time of occurrence of gas generation] + [Time of occurrence of gas floating] > [Time of occurrence of casting surface solidification] The possibility of gas defects is evaluated by the time of occurrence of gas generation and gas floating calculated using the gas constant. The residual position of generated gases is decided by the closed loops indicating the final solidification location in the casting simulation. The above procedure enables us to suggest suitable casting designs with zero gas defects, without the need to repeat casting tests.