• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.9
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• pp.687-692
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• 1998

Silicon doped $Al_{0.32}Ga_{0.68}As$ were growth by molecular beam epitaxy. Electroreflectance(ER) spectra of the $E_1$ transition of Schottky barrier Au/n-$Al_{0.32}Ga_{0.68}As$ have been measured at various modulation voltage($V_{ac}$) and dc bias voltage($V_{bias}$). from the $E_1$peak, band gap energy of the $Al_{0.32}Ga_{0.68}As$ is 1.883 eV which corresponds to an Al composition of 32%. As modulation voltage($V_{bias}$) is changed, a line shape at the $E_1$transition does not change, but its amplitude varies linearly. The amplitude of $E_1$signal decrease with increasing the forward dc bias voltage($V_{bias}$), but the line shape does not change. It suggests that the low field theory rather than Franz-Keldysh oscillation is Required to interpret spectra. Also, spectra at the $E_1$transition were broadened with increasing the reverse dc bias voltage($V_{bias}$) which suggests the presence of Field-induced broadening.

• Journal of the Korean institute of surface engineering
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• v.54 no.3
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• pp.133-138
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• 2021

Ternary Ti-X-N coatings, where X = Al, Si, Cr, O, etc., have been widely used for machining tools and cutting tools such as inserts, end-mills, and etc. Ti-Al-N-O coatings were deposited onto silicon wafer and WC-Co substrates by a cathodic arc evaporation (CAE) technique at various negative substrate bias voltages. In this study, the influence of substrate bias voltages during deposition on the microstructure and mechanical properties of Ti-Al-N-O coatings were systematically investigated to optimize the CAE deposition condition. Based on results from various analyses, the Ti-Al-N-O coatings prepared at substrate bias voltage of -80 V in the process exhibited excellent mechanical properties with a higher compressive residual stress. The Ti-Al-N-O (-80 V) coating exhibited the highest hardness around 30 GPa and elastic modulus around 303 GPa. The improvement of mechanical properties with optimized bias voltage of -80 V can be explained with the diminution of macroparticles, film densification and residual stress induced by ion bombardment effect. However, the increasing bias voltage above -80 V caused reduction in film deposition rate in the Ti-Al-N-O coatings due to re-sputtering and ion bombardment phenomenon.

• Transactions on Electrical and Electronic Materials
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• v.12 no.5
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• pp.209-212
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• 2011

Hafnium nitride (HfN) thin films were deposited onto a silicon substrate by inductive coupled nitrogen plasma-assisted radio frequency magnetron sputtering. The films were prepared without intentional substrate heating and a substrate negative bias voltage ($-V_b$) was varied from -50 to -150 V to accelerate the effects of nitrogen ions ($N^+$) on the substrate. X-ray diffractometer patterns showed that the structure of the films was strongly affected by the negative substrate bias voltage, and thin film crystallization in the HfN (100) plane was observed under deposition conditions of -100 $V_b$ (bias voltage). Atomic force microscopy results showed that surface roughness also varied significantly with substrate bias voltage. Films deposited under conditions of -150 $V_b$ (bias voltage) exhibited higher hardness than other films.

• Journal of the Korean Vacuum Society
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• v.8 no.3B
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• pp.346-352
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• 1999

Diamond-like carbon (DLC) lims were deposited by using end hall type ion gun. Benzene gas was used for the generation of carbon ions. In order to systematically control the ion energy, we applied to the substrate DC, pulsed DC or 250 kHz medium frequency bias voltage, DLC films of superior mechanical properties of hardness 39$\pm$4 GPa and elastic mudulus 290$\pm$50GPa (2 to 6 times better than those of the films deposited by plasma assisted CVD method) could be obtained. Deposition rate was much higher than when using Kaufman type ion source, which results from higher ion beam current of end hall type ion gun. The mechanical properties and atomic bond structure were independent of the bias voltage type ion gun. The mechanical properties and atomic bond structure were independent of the bias voltage type but intimately related with the magnitude of the bias voltage. With increasing the negative bias voltage, the structure of the films changed to graphitic one resulting in decreased content of three dimensional inter-links. Degradation of the mechanical properties with increasing bias voltage could be thus understood in terms of the content odf three dimensional inter-links.

• ETRI Journal
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• v.32 no.3
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• pp.406-413
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• 2010

In order to guarantee the proper operation of a recessed channel array transistor (RCAT) pseudo SRAM, the back-bias voltage must be changed in response to changes in temperature. Due to cell drivability and leakage current, the obtainable back-bias range also changes with temperature. This paper presents a pseudo SRAM for mobile applications with an adaptive back-bias voltage generator with a negative temperature dependency (NTD) using an NTD VBB detector. The proposed scheme is implemented using the Samsung 100 nm RCAT pseudo SRAM process technology. Experimental results show that the proposed VBB generator has a negative temperature dependency of -0.85 $mV/^{\circ}C$, and its static current consumption is found to be only 0.83 ${\mu}A$@2.0 V.

• Korean Journal of Materials Research
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• v.17 no.11
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• pp.618-621
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• 2007

Chromium nitride (CrN) films were deposited on silicon substrate by RF magnetron sputtering assisted by inductive coupled nitrogen plasma without intentional substrate heating. Films were deposited with different levels of bombarding energy by nitrogen ions $(N^+)$ to investigate the influence of substrate bias voltage $(V_b)$ on the growth of CrN thin films. XRD spectra showed that the crystallographic structure of CrN films was strongly affected by substrate bias voltage. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) results showed that surface roughness and grain size of the CrN films varied significantly with bias voltage. For - 80 $V_b$ depositions, the CrN films showed bigger grain sizes than those of other bias voltage conditions. The lowest surface roughness of 0.15 nm was obtained from the CrN films deposited at .130 $V_b$.

• Journal of the Korean institute of surface engineering
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• v.52 no.6
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• pp.342-349
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• 2019

Titanium nitride(TiN) thin films have been deposited on PEN(Polyethylene naphthalate) substrate by reactive RF(13.56 MHz) magnetron sputtering in a 25% N₂/Ar mixed gas atmosphere. The pulsed DC bias voltage of -50V on substrates was applied with a frequency of 350 kHz, and duty ratio of 40%(1.1 ㎲). The effects of pulsed DC substrate bias voltage on the crystallinity, color, electrical properties of TiN_x films have been investigated using XRD, SEM, XPS and measurement of the electrical properties such as electrical conductivity, carrier concentration, mobility. The deposition rates of TiN_x films was decreased with application of the pulsed DC substrate bias voltage. The TiN_x films deposited without and with pulsed bias of -50V to substrate exhibits gray and gold colors, respectively. XPS depth profiling revealed that the introduction of the substrate bias voltage resulted in decreasing oxygen concentration in TiN_x films, and increasing the electrical conductivities, carrier concentration, and mobility to about 10 times, 5 times, and 2 times degree, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.679-682
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• 2006

By adjusting driving voltage, the image quality and optical characteristics have been improved. Based on the experiment results. Optical properties including viewing angle and color shifts at bias voltage 2.4 V are better than those of bias voltage 1 V.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.1 s.343
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• pp.1-6
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• 2006

This paper proposes substrate-bias voltage generator to reduce leakage power consumption of digital logic circuits operating at supply voltage of 0.5V. Proposed substrate-bias voltage generator is composed of VSS and VBB generator. The former circuit produces negative voltage and supplies its output voltage for VBB generator. As a result VBB generator develops much lower negative voltage than that of conventional one. Proposed circuit is fabricated using 0.18um 1Poly-6Metal CMOS process and measurement result demonstrated stable operation with substrate-bias voltage of -0.95V.

• Advances in nano research
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• v.15 no.3
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• pp.263-275
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• 2023

The electron transport properties of Y-type zigzag branched carbon nanotubes (CNTs) are of great significance for micro and nano carbon-based electronic devices and their interconnection. Based on the semi-empirical method combining tight-binding density functional theory and non-equilibrium Green's function, the electron transport properties between the branches of Y-type zigzag branched CNT are studied. The results show that the drain-source current of semiconducting Y-type zigzag branched CNT (8, 0)-(4, 0)-(4, 0) is cut-off and not affected by the gate voltage in a bias voltage range [-0.5 V, 0.5 V]. The current presents a nonlinear change in a bias voltage range [-1.5 V, -0.5 V] and [0.5 V, 1.5 V]. The tangent slope of the current-voltage curve can be changed by the gate voltage to realize the regulation of the current. The regulation effect under negative bias voltage is more significant. For the larger diameter semiconducting Y-type zigzag branched CNT (10, 0)-(5, 0)-(5, 0), only the value of drain-source current increases due to the larger diameter. For metallic Y-type zigzag branched CNT (12, 0)-(6, 0)-(6, 0), the drain-source current presents a linear change in a bias voltage range [-1.5 V, 1.5 V] and is symmetrical about (0, 0). The slope of current-voltage line can be changed by the gate voltage to realize the regulation of the current. For three kinds of Y-type zigzag branched CNT with different diameters and different conductivity, the current-voltage curve trend changes from decline to rise when the branch of drain-source is exchanged. The current regulation effect of semiconducting Y-type zigzag branched CNT under negative bias voltage is also more significant.