• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.301-305
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• 2016

We investigate proton conduction in a nonstoichiometric ${\Sigma}3$ $BaZrO_3$ (210)[001] tilt grain boundary using density functional theory (DFT). We employ the space charge layer (SCL) and structural disorder (SD) models with the introduction of protons and oxygen vacancies into the system. The segregation energies of proton and oxygen vacancy are determined as -0.70 and -0.54 eV, respectively. Based on this data, we obtain a Schottky barrier height of 0.52 V and defect concentrations at 600K, in agreement with the reported experimental values. We calculate the energy barrier for proton migration across the grain boundary core as 0.61 eV, from which we derive proton mobility. We also obtain the proton conductivity from the knowledge of proton concentration and mobility. We find that the calculated conductivity of the nonstoichiometric grain boundary is similar to those of the stoichiometric ones in the literature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.50-53
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• 2001

In this study, gate leakage current mechanism has been analyzed for GaAs MESFET with different temperatures ranging from 27$^{\circ}C$ to 300$^{\circ}C$ . It is expected that the thermionic and field emission at the MS contact will dominate the current flow. Thermal cycle is applied to test the reliability of the device. From the results, it is proved that thermal stress gradually increases the gate leakage current at the same bias conditions and leads to the breakdown and failure mechanism which is critical in the field equipment. Finally the gate contact under the repeated thermal shock has been tested to check the quality of Schottky barrier and the current will be expressed in the analytical from to associate with the electrical characteristics of the device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.263-266
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• 2003

The gate leakage current is first calculated using the experimental method between gate and drain by opening source electrode. Next, the gate to drain current has been obtained with a ground source. The difference of two current has been tested and provide that the existence of another source to Schotuy barrier height against the image force lowering effect.

• Journal of Sensor Science and Technology
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• v.17 no.5
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• pp.346-349
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• 2008

A metal-semiconductor-metal (MSM) ultraviolet (UV) photodetector (PD) is proposed as an effective UV sensing device for integration with a GaN n-channel MISFET on auto-doped p-type GaN grown on a silicon substrate. Due to the high hole barrier of the metal-p-GaN contact, the dark current density of the fabricated MSM PD was less than $3\;nA/cm^2$ at a bias of up to 5 V. Meanwhile, the UV/visible rejection ratio was 400 and the cutoff wavelength of the spectral responsivity was 365 nm. However, the UV/visible ratio was limited by the sub-bandgap response, which was attributed to defectrelated deep traps in the p-GaN layer of the MSM PD. In conclusion, an MSM PD has a high process compatibility with the n-channel GaN Schottky barrier MISFET fabrication process and epitaxy on a silicon substrate.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.2
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• pp.179-184
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• 2016

In recent years, the on-resistance, power loss and cell density of Si power devices have not exhibited significant improvements, and performance is approaching the material limits. GaN is considered an attractive material for future high-power applications because of the wide band-gap, large breakdown field, high electron mobility, high switching speed and low on-resistance. Here we report on the Ohmic contact resistance and reverse-bias characteristics of AlGaN/GaN Schottky barrier diodes with and without annealing. Annealing in oxygen at $500^{\circ}C$ resulted in an increase in the breakdown voltage from 641 to 1,172 V for devices with an anode-cathode separation of $20{\mu}m$. However, these annealing conditions also resulted in an increase in the contact resistance of $0.183{\Omega}-mm$, which is attributed to oxidation of the metal contacts. Auger electron spectroscopy revealed diffusion of oxygen and Au into the AlGaN and GaN layers following annealing. The improved reverse-bias characteristics following annealing in oxygen are attributed to passivation of dangling bonds and plasma damage due to interactions between oxygen and GaN/AlGaN. Thermal annealing is therefore useful during the fabrication of high-voltage GaN devices, but the effects on the Ohmic contact resistance should be considered.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.3
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• pp.354-362
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• 2017

We investigated the improvement in electrical characteristics of large AlGaN/GaN on Si Schottky barrier diode (SBD) induced by structural change to achieve a better trade-off between the forward and reverse performance to obtain high power conversion efficiency in PFC converter. Using an optimized dry etch condition for a large device, we fabricated three-types of SBD with 63 mm channel width: conventional, recessed, recessed dual-anode-metal SBD. The recessed dual-anode-metal SBD exhibited a very low turn-on voltage of 0.34 V, a high forward current of 1.63 A at 1.5 V, a leakage current of $114{\mu}A$ at -15 V, a breakdown voltage of 794 V.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.105-113
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• 2010

In this paper, a 1.485 Gbps video signal transmission system using the carrier frequency of 240 GHz band was designed and simulated. The sub-harmonic mixer based on Schottky barrier diode was simulated in the transmitter and receiver. Both of heterodyne and direct detection receivers were simulated for each performance analysis. The ASK modulation was used in the transmitter and the envelop detection method was used in the receiver. The transmitter simulation results showed that the RF output power was -11.4 dBm($73{\mu}W$), when the IF input power was -3 dBm(0.5 mW) at the LO power of 7 dBm(5 mW) in sub-harmonic mixer, which corresponds to SSB(Single Side Band) conversion loss of 8.4 dB. This value is similar to the conversion loss of 8.0 dB(SSB) of VDI's commercial model WR3.4SHM(220~325 GHz) at 240 GHz. The combined transmitter and receiver simulation results showed that the recovered signal waveforms were in good agreement to the transmitted 1.485 Gbps NRZ signal.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.4
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• pp.35-40
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• 2002

Ultra-power-saving SBR has been fabricated by using vanadium and molybdenum with low work function. Because reverse leakage current is increased in inverse proportion to work function, we implanted argon ion on the n-Si layer for decreasing leakage current. The dose and acceleration energy of the argon implantation in the silicon was 1$\times$10$^{14}$ ion/$\textrm{cm}^2$, 40 keV, respectively. The forward voltages drop of fabricated V-SBR and Mo-SBR were 0.25 V and 0.39 V at the same forward current density of 60 A/$\textrm{cm}^2$. As a result, it was found that the reverse leakage current of the fabricated V-SBR was reduced over 20$mutextrm{A}$ by the argon implantation in comparison with the no implanted V-SBR. Also, owing to argon implantation, the inferiority of characteristic of the SBR was not detected.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.1
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• pp.13-20
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• 2000

In this paper, we demonstrated an analytical description method of forward votage drop and reverse leakage current of the junction barrier controlled schottky rectifier with linearly graded junction and abrupt junction models. In this case, the vertical depths of device are 1[${\mu}{\textrm}{m}$] and 2[${\mu}{\textrm}{m}$], respectively. Through ion implantation and annealing process, we obtain the data of lateral and depth from implanted 2-dimensional profiles. Also we applied these data to models that indicate the change of depletion each on linearly-graded and abrupt juction as the forward and revers bias. After applied depletion changes to electric characteristics of JBS rectifiers, we calculated the forward I-V, the reverse leakage current and temperatures vs. power dissipations according to each junction. When we compared the rectifier with calculated and measured data, from the calculated results, forward votage drop with linearly graded junction is lower than that of abrupt junction and reverse leakage current with linearly graded junction is lower(≒1$\times$10\ulcorner times) than that of abrupt junction. Also, the power dissipations according to different juction depth(1[${\mu}{\textrm}{m}$], 2[${\mu}{\textrm}{m}$]) of device are calculated. Seeing the calculated results, we confirmed it from analytic model that the rectifier with linearly graded junction retained a low power dissipation up to 600[$^{\circ}C$] in comparison with the rectifier with abrupt junction.

• Journal of the Korean Vacuum Society
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• v.12 no.2
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• pp.123-129
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• 2003

Thin transparent Cu films in the thickness range of 10 ~ 40 nm are deposited by rf-magnetron sputtering on porous silicon (PS) anodized on p-type silicon in dark. Microstructural features of the Cu films are investigated using SEM, AFM and XRD techniques. The RMS roughness of the Cu films is found to be around 1.47 nm and the grain growth is columnar with a (111) preferred orientation and follows the Volmer-Weber mode. The photoluminescence studies showed that a broad luminiscence peak of PS near the blue-green region gets blue shifted (~0.05 eV) with a small reduction in intensity and therefore, Cu-related PL quenching is absent. The FTIR absorption spectra on the PS/Cu structure revealed no major change of the native PS peaks but only a reduction in the relative intensity. The I-V characteristic curves further establish the Schottky nature of the diode with an ideality factor of 2.77 and a barrier height of 0.678 eV. An electroluminiscence (EL) signal of small intensity could be detected for the above diode.