• Journal of Sensor Science and Technology
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• v.23 no.2
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• pp.114-121
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• 2014

We report a polysilicon active area membrane field effect transistor (PSAFET) pressure sensor for low stress deflection of membrane. The PSAFET was produced in conventional FET semiconductor fabrication and backside wet etching. The PSAFET located at the front side measured pressure change using 300 nm thin-nitride membrane when a membrane was slightly strained by the small deflection of membrane shape from backside with any physical force. The PSAFET showed high sensitivity around threshold voltage, because threshold voltage variation was composed of fractional function form in sensitivity equation of current variation. When gate voltage was biased close to threshold voltage, a fractional function form had infinite value at $V_{tn}$, which increased the current variation of sensitivity. Threshold voltage effect was dominant right after the PSAFET was turned on. Narrow transistor channel established by small current flow was choked because electron could barely cross drain-source electrodes. When gate voltage was far from threshold voltage, threshold voltage effect converged to zero in fractional form of threshold voltage variations and drain current change was mostly determined by mobility changes. As the PSAFET fabrication was compatible with a polysilicon FET in CMOS fabrication, it could be adapted in low pressure sensor and bio molecular sensor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.7
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• pp.563-568
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• 2012

Indium tin oxide (ITO) films were prepared using radio frequency (RF) magnetron sputtering method, magnets were equipped near the target in the sputter to bring the plasma near the target. The effect of magnetic field that brings the plasma near the substrate was compared with that of substrate heating. The effect of substrate heating on the grain size of the ITO thin film was larger than that of the magnetic field. However, the grain size of the ITO thin film was larger when the magnetic field was applied near the substrate during the sputtering process than when the substrate was not heated and the magnetic field was not applied. If stronger magnetic field is applied near the substrate during sputtering, it can be expected that the ITO thin film with good electrical conductivity and high transparency is obtained at low substrate temperature. When magnetic field of 90 Gauss was applied near the substrate during sputtering, the mobility of the ITO thin film increased from 15.2 $cm^2/V.s$ to 23.3 $cm^2/V.s$, whereas the sheet resistivity decreased from 7.68 ${\Omega}{\cdot}cm$ to 5.11 ${\Omega}{\cdot}cm$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.6-9
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• 2000

InSb hall effect of multilayerd structures were investigated. According to variation of magnetic field measured hall coefficient, Hall mobility, carrier density and hall voltage. For the measurement of electrical properties of hall device, evaperated InSb thin film fabricated with series and parallel multilayers. We found that the XRD analysis of InSb thin film showed good properties at $200^{\circ}C$, 60 minutes. Resistance of ohmic contact increased linearly due to increasing current. Some of device fabrication technique and analysis of Hall effect were discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.21-24
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• 2000

lnSb temperature dependent hall effect of multilayerd structures were investigated. According to variation of magnetic field measured hall coefficient, Hall mobility, carrier density and hall voltage. For the measurement of electrical properties of hall device, evaperated InSb thin film fabricated with series and parallel multilayers. We found that the XRD analysis of InSb thin film showed good properties at 20$0^{\circ}C$, 60 minutes. Resistance of ohmic contact increased linearly due to increasing current. Some of device fabrication technique and analysis of Hall effect were discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.287.2-287.2
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• 2016

Silicon has considerably good characteristics on electron, hole mobility and its price. With 2-D sinlge-layer Graphene/n-Si heterojunction solar cell shows that in one sun condition exhibit power conversion efficiency(PCE) of 10.1%. This photovoltaic effect was achieved by applying gate voltage to the Schottky junction of the heterostructure solar cell. Energy band diagram shows that Schottky barrier between Si and graphene can be adjust by the external electric field. because of the fermi level of the graphene can be changed by external gate voltage, we can control the Schottkky barrier of the heterostructure solar cell. The ratio between generated power of solar cell and consumption electrical power is remarkable. Since we use the graphene as the top gate electrode, most of the sun light can penetrate into the active area.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.1
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• pp.14-18
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• 2007

The electric property in the $GaAs-Al_{x}Ga_{1-x}$ quantum well with the Si ${\delta}-doping$ layer in a non-central position is studied through the effect of the electric field intensity on the electron distribution. The finite difference method is used for the calculation of the subband energy level and its wavefunction. In order to account for the change of the potential energy due to the charged particles, the self consistent method is employed. As the Si ${\delta}-doping$ layer becomes closer to the heterojunction interface, the electrons less affected by Coulomb scattering are greatly increased under the external electric field. Therefore, the high speed device is suggested due to the fact that the high mobility electrons can be increased by positioning the ${\delta}-doping$ layer in the quantum well and by applying the electric field intensity.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.984-999
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• 2010

A long-term field demonstration experiment of selected stabilization method to reduce the heavy metal mobility in farmland soil contaminated by heavy metals around abandoned mine site was conducted. Field demonstration experiments were established on the contaminated farmland with the wooden plate(thickness=1cm) which dimension were width=200cm, Length=200cm, height=80cm and filled with treated soil, which was mixed with lime stone and steel refining slag except on control plot. Soil samples in the plots were collected and analyzed during the experiment period(2008. 2~2008. 8) after the installation of the plots. Field demonstration experiments results showed that the application ratio of lime stone 5% was effective for immobilizing heavy metal components in contaminated farmland soil.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.281.2-281.2
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• 2016

Two-dimensional van der Waals (2D vdWs) materials have been extensively studied for future electronics and materials sciences due to their unique properties. Among them, black phosphorous (BP) has shown infinite potential for various device applications because of its high mobility and direct narrow band gap (~0.3 eV). In this work, we demonstrate a few-nm thick BP-based nonvolatile memory devices with an well-known poly(vinylidenefluoride-trifluoroethylene) [P(VDF-TrFE)] ferroelectric polymer gate insulator. Our BP ferroelectric memory devices show the highest linear mobility value of $1159cm^2/Vs$ with a $10^3$ on/off current ratio in our knowledge. Moreover, we successfully fabricate the ferroelectric complementary metal-oxide-semiconductor (CMOS) memory inverter circuits, combined with an n-type $MoS_2$ nanosheet transistor. Our memory CMOS inverter circuits show clear memory properties with a high output voltage memory efficiency of 95%. We thus conclude that the results of our ferroelectric memory devices exhibit promising perspectives for the future of 2D nanoelectronics and material science. More and advanced details will be discussed in the meeting.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.302.1-302.1
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• 2016

Solution-processed amorphous metal-oxide thin-film transistors (TFTs) are considered as promising candidates for the upcoming transparent and flexible electronics due to their transparent property, good performance uniformity and possibility to fabricate at a low-temperature. In addition, solution processing metal oxide TFTs may allow non-vacuum fabrication of flexible electronic which can be more utilizable for easy and low-cost fabrication. Recently, for high-mobility oxide TFTs, multi-layered oxide channel devices have been introduced such as superlattice channel structure and heterojunction structure. However, only a few studies have been mentioned on the bias illumination stress in the multi- layered oxide TFTs. Therefore, in this research, we investigated the effects of bias illumination stress in solution-processed bilayer oxide TFTs which are fabricated by the deep ultraviolet photochemical activation process. For studying the electrical and stability characteristics, we implemented positive bias stress (PBS) and negative bias illumination stress (NBIS). Also, we studied the electrical properties such as field-effect mobility, threshold voltage ($V_T$) and subthreshold slop (SS) to understand effects of the bilayer channel structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.149-150
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• 2006

A ZnO nanowire-based FET is fabricated m this study on a flexible substrate of PES. For the flat and bent flexible substrates, the current ($I_D$) versus drain-source bias voltage ($V_{DS}$) and $I_D$ versus gate voltage ($V_G$) results are compared. The flat band was Ion/Ioff ratio of ${\sim}10^7$, a transconductance of 179 nS and a mobility of ~10.104 cm2/Vs at $V_{DS}$ =1 V. Also bent to a radius curvature of 0.15cm and experienced by an approximately strain of 0.77 % are exhibited an Ion/Ioff ratio of ${\sim}10^7$, a transconductance of ~179 nS and a mobility of ${\sim}10.10 cm^2/Vs$ at $V_{DS}$ = 1V. The electrical characteristics of the FET are not changed very much. although the large strain is given on the device m the bent state.