• Title/Summary/Keyword: passivation current density

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Corrosion Behavior of Titanium for Implant in Simulated Body Fluids (인공 체액 조건에서 임플랜트용 티타늄 소재의 부식 특성)

  • 이중배;최기열
    • Journal of the Korean institute of surface engineering
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    • v.37 no.2
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    • pp.110-118
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    • 2004
  • The corrosion of pure titanium (CP- Ti Grade 2) and titanium alloy (Ti6Al4V ELI) were studied under various conditions of simulated body fluids. The static immersion test and the electrochemical test were performed in accordance with ISO 10271 : 2001. For the electrochemical test, the open circuit potential was monitored as a function of time, and the cyclic polarization curve was recorded. The corrosion resistance was evaluated from the values of corrosion potential, passivation current density, breakdown potential, and the shape of hysteresis etc. The effects of alloy type, surface condition, temperature, oxygen, and constituents in the fluids such as acid, chloride were estimated. Both specimens had extremely low dissolution rate in the static immersion test. They showed strong passivation characteristics in the electrochemical test. They maintained negligible current density throughout the wide anodic potential range. The passive layer was not broken up to 2.0 V (vs. SCE). The hysteresis and the shift of passivation potential toward the anodic direction was observed during the reversed scan. The passivation process appeared to be accelerated by oxygen in air or that dissolved in the fluids. The passivation also proceeded without oxygen by the reaction of constituents in the fluids. Acid or chloride in the fluids, specially later weakened the passive layer, and then induced higher passivation current density and less shift of passivation potential in the reversed scan. CP-Ti Grade 2 was more reactive than Ti6Al4V ELI in the fluids containing acid or chloride, but thicker layer produced on its surface provided higher corrosion resistance.

Improved Dit between ALD HfAlO Dielectric and InGaAs Substrate Using NH3 Plasma Passivation (InGaAs 위의 NH3 Plasma Passivation을 이용한 ALD HfAlO유전체 계면전하(Dit) 향상)

  • Choi, Jae Sung
    • Journal of the Semiconductor & Display Technology
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    • v.17 no.4
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    • pp.27-31
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    • 2018
  • The effect of $NH_3$ plasma passivation on the chemical and electrical characteristics of ALD HfAlO dielectric on the InGaAs substrate was investigated. The results show that $NH_3$ plasma passivation exhibit better electrical & chemical performance such as much lower leakage current, lower density of interface trap(Dit) level, and low unstable interfacial oxide. $NH_3$ plasma passivation can effectively enhance interfacial characteristics. Therefore $NH_3$ plasma passivation improved the HfAlO dielectric performance on the InGaAs substrate.

Surface Passivation Method for GaN UV Photodetectors Using Oxygen Annealing Treatment

  • Lee, Chang-Ju;Park, Hongsik
    • Journal of Sensor Science and Technology
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    • v.25 no.4
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    • pp.252-256
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    • 2016
  • Epitaxially grown GaN layers have a high surface state density, which typically results in a surface leakage current and a photoresponse in undesirable wavelengths in GaN optoelectronic devices. Surface passivation is, therefore, an important process necessary to prevent performance degradation of GaN UV photodetectors. In this study, we propose oxygen-enhanced thermal treatment as a simple surface passivation process without capping layers. The GaN UV photodetector fabricated using a thermal annealing process exhibits improved electrical and photoresponsive characteristics such as a reduced dark current and an enhanced photoresponsive current and UV-to-visible rejection ratio. The results of this study show that the proposed surface passivation method would be useful to enhance the reliability of GaN-based optoelectronic devices.

The effects of sulfur passivation on the performance of ITO/InP solar cells (ITO/InP 태양전지 제작에 응용된 sulfur passivation의 효과)

  • 이영철;한교용
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.34D no.9
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    • pp.50-55
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    • 1997
  • In order to improve the electrical performance of ITO/InP solar cells, sulfur passivation technique was employed using (N $H_{4}$)$_{2}$ $S_{x}$ solution. Passivation effects were analyzed by measuring the short circuit current density ( $J_{sc}$ ) of solar cells and photoluminescence (PL) of ITO/InP interfaces. This paper firstly reports the sulfur passivation effects by investigating the correlation between the PL intensity and the short circuit current. Generally, PL intensity and the short circuit current of sulfur passivated sampels wer eincreased, and showed the same trend. Especially, samples prepared at 60.deg. C (N $H_{4}$)$_{2}$ $S_{x}$ solution exhibited the highest $J_{sc}$ and PL intensity. These results demonstrated that the short circuit currents was influenced by the ITO/InP interface states.

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Impact of Passivation and Reliability for Base-exposed InGaP/GaAs HBTs

  • Park, Jae-Woo
    • Transactions on Electrical and Electronic Materials
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    • v.8 no.3
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    • pp.115-120
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    • 2007
  • Reliability between passivated and unpassivated process with the base-exposed InGaP/GaAs HBTs was studied. A passivation of HBT was attempted by $SiO_2$ thin film deposition at $300^{\circ}C$ by means of PECVD. Base-exposed InGaP/GaAs HBTs before and after passivation were investigated and compared in terms of DC and RF performance. Over a total period of 30 days, passivated HBTs show only 2% degradation of DC current gain for the high current density of $40KA/cm^2$. The measured thermal resistance of $2{\times}30{\mu}m^2$ single emitter InGaP/GaAs HBT passivated with PECVD $SiO_2$ devices can be extracted and was founded to be 1430 K/W. The estimated MTTF was $2{\times}10^7hr\;at\;T_j=125^{\circ}C$ with an activation energy $(E_a)$ of 1.37 eV.

Transparent Sol-Gel Hybrid Dielectric Material Coatings for Low k Passivation Layer

  • Yang, Seung-Cheol;Oh, Ji-Hoon;Kwak, Seung-Yeon;Bae, Byeong-Soo
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.1453-1456
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    • 2009
  • Transparent sol-gel hybrid dielectric material (hybrimer) coating films were fabricated by spin coating and photo or thermal curing of sol-gel derived oligosiloxane resins. Hybrimer coating films are suitable as the passivation layer of TFT in AMLCD due to low dielectric constant, small loss tangent, low leakage current density, high transmittance and thermal stability.

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A Study on the Performance Improvement of GaAs Metamorphic HEMTs Using ICPCVD SiNx Passivation (ICPCVD 질화막 Passivation을 이용한 GaAs Metamorphic HEMT 소자의 성능개선에 관한 연구)

  • Kim, Dong-Hwan
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.4
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    • pp.483-490
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    • 2009
  • In this paper, a novel low-damage silicon nitride passivation for 100nm InAlAs/InGaAs MHEMTs has been developed using remote ICPCVD. The silicon nitride deposited by ICPCVD showed higher quality, higher density, and lower hydrogen concentration than those of silicon nitride deposited by PECVD. In particular, we successfully minimized the plasma damage by separating the silicon nitride deposition region remotely from ICP generation region, typically with distance of 34cm. The silicon nitride passivation with remote ICPCVD has been successfully demonstrated on GaAs MHEMTs with minimized damage. The passivated devices showed considerable improvement in DC characteristics and also exhibited excellent RF characteristics($f_T$of 200GHz).The devices with remote ICPCVD passivation of 50nm silicon nitride exhibited 22% improvement(535mS/mm to 654mS/mm) of a maximum extrinsic transconductance($g_{m.max}$) and 20% improvement(551mA/mm to 662mA/mm) of a maximum saturation drain current ($I_{DS.max}$) compared to those of unpassivated ones, respectively. The results achieved in this work demonstrate that remote ICPCVD is a suitable candidate for the next-generation MHEMT passivation technique.

Effects of Niobium Addition on the Corrosion Behavior of Ti Alloys in NaCl Solution (NaCl 용액에서 Nb 첨가가 Ti 합금의 부식 거동에 미치는 영향)

  • Kim, E.S.;Kim, W.G.;Choe, H.C.
    • Corrosion Science and Technology
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    • v.12 no.1
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    • pp.34-39
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    • 2013
  • In this study, the effect of niobium addition on the passivation behavior of Ti alloys in NaCl solution was investigated using various electrochemical methods. An ${\alpha}$-phase in Ti alloy was transformed into a ${\beta}$-phase and martensite structure decreased as Nb content increased. The corrosion and passivation current density($+300mV_{SCE}$) decreased as Nb content increased, and thereby a stable passive film was formed on the Ti alloy. Potential of Ti-xNb alloy in the passive region increased, whereas, current density decreased with time from results of potentiostatic and galvanostatic tests. Also, the corrosion morphology showed the smaller pits as Nb content increased. Consequently, Ti alloy contained high Nb content showed a good resistance to pitting corrosion in 0.9% NaCl solution.

Performance of an InAs/GaSb Type-II Superlattice Photodiode with Si3N4 Surface Passivation

  • Kim, Ha Sul
    • Current Optics and Photonics
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    • v.5 no.2
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    • pp.129-133
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    • 2021
  • This study observed the performance of an InAs/GaSb type-II superlattice photodiode with a p-i-n structure for mid-wavelength infrared detection. The 10 ML InAs/10 ML GaSb type-II superlattice photodiode was grown using molecular beam epitaxy. The cutoff wavelength of the manufactured photodiode with Si3N4 passivation on the mesa sidewall was determined to be approximately 5.4 and 5.5 ㎛ at 30 K and 77 K, respectively. At a bias of -50 mV, the dark-current density for the Si3N4-passivated diode was measured to be 7.9 × 10-5 and 1.1 × 10-4 A/㎠ at 77 K and 100 K, respectively. The differential resistance-area product RdA at a bias of -0.15 V was 1481 and 1056 Ω ㎠ at 77 K and 100 K, respectively. The measured detectivity from a blackbody source at 800 K was calculated to be 1.1 × 1010 cm Hz1/2/W at zero bias and 77 K.

Effectiveness of parylene coating on CdZnTe surface after optimal passivation

  • B. Park;Y. Kim;J. Seo;K. Kim
    • Nuclear Engineering and Technology
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    • v.54 no.12
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    • pp.4693-4697
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    • 2022
  • Parylene coating was adopted on CdZnTe (CZT) detector as a mechanical protection layer after wet passivation with hydrogen peroxide (H2O2) and ammonium fluoride (NH4F). Wet chemical passivant lose their effectiveness when exposed to the ambient conditions for a long time. Parylene coating could protect the effectiveness of passivation, by mechanically blocking the exposure to the ambient conditions. Stability of CZT detector was tested with the measurement of leakage current density and response to radio-isotopes. When the enough thickness of parylene (>100 ㎛) is adopted, parylene is a promising protection layer thereby ensuring the performance and long-term stability of CZT detectors.