• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.487-493
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• 1997

Ti/sic(4H) Schottky barrier diodes were fabricated. The donor concentration and the built-in potential obtained by capacitance-voltage(C-V) measurement was about $2.0{\times}10^{15}{\textrm}{cm}^{-3}$ and 0.65 V, respectively. The ideality factor of 1.07 was obtained from the slope of current-voltage(I-V) characteristics at low current density. The breakdown field under the reverse bias voltage was about $1.7{\times}10^3V/{\textrm}{cm}$ and was very high. The barrier height of Ti for SiC(4H) was 0.91 V, which was determined by the analysis of the saturation current-temperature and the C-V characteristics.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.343-346
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• 2004

This paper proposes a leakage-suppressed SRAM with dynamic power saying scheme for the future leakage-dominant sub-70-nm technology. By dynamically controlling the common source-line voltage ($V_{SL}$) of sleep cells, the sub-threshold leakage through these sleep cells can be reduced to be 1/10-1/100 due to the reverse body-bias effect, dram-induced barrier lowering (DIBL) and negative $V_{GS}$ effects. Moreover, the bit-ling leakage which mar introduce a fault during the read operation can be completely eliminated in this new SRAM. The dynamic $V_{SL}$ control can also reduce the bit-line swing during the write so that the dynamic power in write can be reduced. This new SRAM was fabricated in 0.35-${\mu}m$ CMOS process and more than $30\%$ of dynamic power saying is experimentally verified in the measurement. The leakage suppression scheme is expected to be able to reduce more than $90\%$ of total SRAM power in the future leakage-dominant 70-nm process.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.5
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• pp.682-687
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• 2014

We have performed reverse gate bias stress tests on AlGaN/GaN-on-Si Heterostructure FETs (HFETs). The shift of threshold voltage ($V_{th}$) and the reduction of on-current were observed from the stressed devices. These changes of the device parameters were not permanent. We investigated the temporary behavior of the stressed devices by analyzing the temperature dependence of the instabilities and TCAD simulation. As the baseline temperature of the electrical stress tests increased, the changes of the $V_{th}$ and the on-current were decreased. The on-current reduction was caused by the positive shift of the $V_{th}$ and the increased resistance of the gate-to-source and the gate-to-drain access region. Our experimental results suggest that electron-trapping effect into the shallow traps in devices is the main cause of observed instabilities.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.8-11
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• 1997

This study makes SrTiO$_{3}$ with nonpolarity among ferroelectrics by RF sputtering as dielectric layer, produces thin film of Si/SrTiO$_{3}$ and Si/Ti/SrTiO$_{3}$ of MOS structure using Ti as buffer layer, measures and examines the electrical features with optical refractive index, absorption rate, permittivity, photon energy and as a result, ferroelectrics oscillation occurrs by the interaction within a film by light temperature and the absorption of thin film with Ti as buffer layer is increased. It is found that the pea\ulcorner of permittivity value of Ti/SrTiO$_{3}$ thin film has low values and is appeared late and as dipole which is found in dielectric is shown, the experiment satisfies the theory In the nature of permittivity by photon energy, imaginary value is higher and current variation slope of thin film of thickness SrTiO$_{3}$ has lower values in reverse bias.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.834-838
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• 2002

In this paper, we have fabricated 4H-SiC schottky diodes utilizing a metal-oxide overlap structure for electric filed termination. The barrier height and Ideality factor were measured by current-voltage, capacitance-voltage characteristics. Schottky barrier height(SBH) were 1.41ev for Ni and 1.35eV for Pt, 1.52eV for Pt/Ti at room temperature and Pt/Ti Schottky diode exhibited Ideality factor was 1.06 to 1.4 in the range of $25^{\circ}C{\sim}200^{\circ}C$. To improve the reverse bias characteristics, an edge termination technique is employed for Pt/Ti/4H-SiC Schottky rectifiers and the device show excellent characteristics with higher blocking voltage up to 780V compared with unterminated devices.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.26.1-26.1
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• 2011

We investigated the atomic layer deposition (ALD) process for nitrogen doped ZnO and the application for n-ZnO : N/p-Si (NW) coaxial hetero-junction photodetectors. ALD ZnO:N was deposited using diethylzinc (DEZ) and diluted $NH_4OH$ at $150^{\circ}C$ of substrate temperature. About 100~300 nm diameter and 5 um length of Si nanowires array were prepared using electroless etching technique in 0.108 g of $AgNO_3$ melted 20 ml HF liquid at $75^{\circ}C$. TEM images showed ZnO were deposited on densely packed SiNW structure achieving extraordinary conformality. When UV (360 nm) light was illuminated on n-ZnO:N/p-SiNW, I-V curve showed about three times larger photocurrent generation than film structure at 10 V reverse bias. Especially, at 660 nm wave length, the coaxial structure has 90.8% of external quantum efficiency (EQE) and 0.573 A/W of responsivity.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.4
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• pp.178-184
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• 2005

In this paper, using diplexer structure and varactor diode controlled by reverse bias voltage for diplexer switch gives possibilities to improve isolation and current characteristics. 1 have newly designed switch with high isolation by application varactor diode corresponding to capacitor of diplexer. The low-pass filter for proposed tunable diplexer passes the microwave signal in the bandwidth for wireless cellular network systems and high-pass filter passes it in the bandwidth for wireless personal communication services (PCS) network systems. As the capacitance of the low-pass filter increases, the cut-off frequency can be moved to low frequency, so that the switch is on state in cellular bandwidth and off state in the PCS bandwidth, in contrast to, as the capacitance for attenuation characteristic of high-pass filter increases, it can be moved to high frequency, so that the switch is off state and on state in the cellular bandwidth. it is possible to improve isolation and current consumption characteristics by application diplexer design methods and varactor diode. 1 expect that the tunable diplexer circuit and design methods should be able to find applications on MMIC and low temperature copired ceramic (LTCC).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.883-888
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• 2007

Investigation of improving the properties of UV detector which uses the wide bandgap of ZnO are under active progress. The present study focused on the design and fabrication of i-ZnO/p-inversion $layer/n^--Si$ Epi. which is characterized with very thin p-type inversion layer for UV detectors. The i-ZnO thin film for achieving p-inversion layer which was grown by RF sputtering at $450^{\circ}C$ and then annealed at $400^{\circ}C$ in $O_2$ gas for 20 min shows good intrinsic properties. High (0002) peak intensity of the i-ZnO film is shown on XRD spectrum and it is confirmed by XPS analysis that the ratio of Zn : O of the i-ZnO film is nearly 1 : 1. Measurement shows high transmission of 79.5 % in UV range (< 400 nm) for the i-ZnO film. Measurement of $V_r-I_{ph}$ shows high UV photo-current of 1.2 mA under the reverse bias of 30 V.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.385-385
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• 2012

A two terminal N+/P/N+ junction device to replace the conventional selective transistor was studied as a bilateral switching device for spin transfer torque (STT) MRAM based on 3D device simulation. An N+/P/N+ junction structure with $30{\times}30nm$ area requires bi-directional current flow enough to write a data by a drain induced barrier lowering (DIBL) under a reverse bias at N+/P (or P/N+ junction), and high current on/off ratio of 106. The SiGe materials are widely used in hetero-junction bipolar transistors, bipolar compensation metal-oxide semiconductors (BiCMOS) since the band gap of SiGe materials can be controlled by changing the fraction and the strain epilayers, and the drift mobility is increased with the increasing Ge content. In this work, N+/P/N+ SiGe material based junction provides that drive current is increased from 40 to $130{\mu}A$ by increased Ge content from 10~80%. When Ge content is about 20%, the drive current density of SiGe device substantially increased to 2~3 times better than Si-based junction device in case of 28 nm P length, which is sufficient current to operation of STT-MRAM.

• Korean Journal of Materials Research
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• v.27 no.7
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• pp.364-368
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• 2017

We performed temperature dependent current-voltage (I-V) measurements to characterize the electrical properties of $Au/Al_2O_3/n-Ge$ metal-insulator-semiconductor (MIS) diodes prepared with and without $H_2O$ prepulse treatment by atomic layer deposition (ALD). By considering the thickness of the $Al_2O_3$ interlayer, the barrier height for the treated sample was found to be 0.61 eV, similar to those of Au/n-Ge Schottky diodes. The thermionic emission (TE) model with barrier inhomogeneity explained the final state of the treated sample well. Compared to the untreated sample, the treated sample was found to have improved diode characteristics for both forward and reverse bias conditions. These results were associated with the reduction of charge trapping and interface states near the $Ge/Al_2O_3$ interface.