• Title/Summary/Keyword: AlAs layer-by-layer deposition

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Evaluation of 1.3-㎛ Wavelength VCSELs Grown by Metal Organic Chemical Vapor Deposition for 10 Gb/s Fiber Transmission

  • Park, Chanwook;Lee, Seoung Hun;Jung, Hae Won;An, Shinmo;Lee, El-Hang;Yoo, Byueng-Su;Roh, Jay;Kim, Kyong Hon
    • Journal of the Optical Society of Korea
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    • v.16 no.3
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    • pp.313-317
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    • 2012
  • We have evaluated a 1.3 ${\mu}m$ vertical-cavity surface-emitting laser (VCSEL), whose bottom mirror and central active layer were grown by metal organic chemical vapor deposition (MOCVD) and whose top mirror was covered with a dielectric coating, for 10 Gb/s data transmission over single-mode fibers (SMFs). Successful demonstration of error-free transmission of the directly modulated VCSEL signals at data rate of 10 Gb/s over a 10 km-long SMF was achieved for operating temperatures from $20^{\circ}C$ to $60^{\circ}C$ up to bit-error-rate (BER) of $10^{-12}$. The DC bias current and modulation currents are only 7 mA and 6 mA, respectively. The results indicate that the VCSEL is a good low-power consuming optical signal source for 10 GBASE Ethernet applications under controlled environments.

Development of a PLD heater for continuous deposition and growth of superconducting layer

  • Jeongtae Kim;Insung Park;Gwantae Kim;Taekyu Kim;Hongsoo Ha
    • Progress in Superconductivity and Cryogenics
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    • v.25 no.2
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    • pp.14-18
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    • 2023
  • Superconducting layers deposited on the metal substrate using the pulsed laser deposition process (PLD) play a crucial role in exploring new applications of superconducting wires and enhancing the performance of superconducting devices. In order to improve the superconducting property and increase the throughput of superconducting wire fabricated by pulsed laser deposition, high temperature heating device is needed that provides high temperature stability and strong durability in high oxygen partial pressure environments while minimizing performance degradation caused by surface contamination. In this study, new heating device have been developed for PLD process that deposit and growth the superconducting material continuously on substrate using reel-to-reel transportation apparatus. New heating device is designed and fabricated using iron-chromium-aluminum wire and alumina tube as a heating element and sheath materials, respectively. Heating temperature of the heater was reached over 850 ℃ under 700 mTorr of oxygen partial pressure and is kept for 5 hours. The experimental results confirm the effectiveness of the developed heating device system in maintaining a stable and consistent temperature in PLD. These research findings make significant contributions to the exploration of new applications for superconducting materials and the enhancement of superconducting device performance.

Effect of negative oxygen ion bombardment on the gate bias stability of InGaZnO

  • Lee, Dong-Hyeok;Kim, Gyeong-Deok;Hong, Mun-Pyo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.160-160
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    • 2015
  • InGaZnO (IGZO) thin-film transistors (TFTs) are very promising due to their potential use in high performance display backplane [1]. However, the stability of IGZO TFTs under the various stresses has been issued for the practical IGZO applications [2]. Up to now, many researchers have studied to understand the sub-gap density of states (DOS) as the root cause of instability [3]. Nomura et al. reported that these deep defects are located in the surface layer of the IGZO channel [4]. Also, Kim et al. reported that the interfacial traps can be affected by different RF-power during RF magnetron sputtering process [5]. It is well known that these trap states can influence on the performances and stabilities of IGZO TFTs. Nevertheless, it has not been reported how these defect states are created during conventional RF magnetron sputtering. In general, during conventional RF magnetron sputtering process, negative oxygen ions (NOI) can be generated by electron attachment in oxygen atom near target surface and accelerated up to few hundreds eV by self-bias of RF magnetron sputter; the high energy bombardment of NOIs generates bulk defects in oxide thin films [6-10] and can change the defect states of IGZO thin film. In this study, we have confirmed that the NOIs accelerated by the self-bias were one of the dominant causes of instability in IGZO TFTs when the channel layer was deposited by conventional RF magnetron sputtering system. Finally, we will introduce our novel technology named as Magnetic Field Shielded Sputtering (MFSS) process [9-10] to eliminate the NOI bombardment effects and present how much to be improved the instability of IGZO TFTs by this new deposition method.

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Study on the Structural Stability and Charge Trapping Properties of High-k HfO2 and HFO2/Al2O3/HfO2 Stacks (High-k HfO2와 HfO2/Al2O3/HfO2 적층막의 구조 안정성 및 전하 트랩핑 특성 연구)

  • Ahn, Young-Soo;Huh, Min-Young;Kang, Hae-Yoon;Sohn, Hyunchul
    • Korean Journal of Metals and Materials
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    • v.48 no.3
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    • pp.256-261
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    • 2010
  • In this work, high-k dielectric stacks of $HfO_2$ and $HfO_2$/$Al_2O_3$/$HfO_2$ (HAH) were deposited on $SiO_2/Si$ substrates by atomic layer deposition as charge trapping layers in charge trapping devices. The structural stability and the charge trapping characteristics of such stacks were investigated using Metal-Alumina-Hafnia-Oxide-Silicon (MAHOS) structure. The surface roughness of $HfO_2$ was stable up to 11 nm with the insertion of 0.2 nm thick $Al_2O_3$. The effect of the thickness of the HAH stack and the thickness of intermediate $Al_2O_3$ on charge trapping characteristics were investigated for MAHOS structure under various gate bias pulse with duration of 100 ms. The threshold voltage shift after programming and erase showed that the memory window was increased with increasing bias on gate. However, the programming window was independent of the thickness of HAH charge trapping layers. When the thickness of $Al_2O_3$insertion increased from 0.2 nm to 1 nm, the erase window was decreased without change in the programming window.

The characteristics of AlN buffered GaN on ion beam modified Si(111) substrates (Si(111) 위에 Ion beam 처리 후 AlN layer를 완충층으로 이용하여 성장시킨 GaN의 특성)

  • Kwang, Min-Gu;Chin, Jeong-Geun;Lee, Jae-Seok;Oh, Seung-Seok;Hyun, Jin;Byun, Dong-Jin
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.03a
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    • pp.99-99
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    • 2003
  • The growth of GaN on Si is of great interest due to the several advantages : low cost, large size and high-quality wafer availability as well as its matured technology. The crystal quality of GaN is known to be much influenced by the surface pretreatment of Si substrate[1]. In this work, the properties of GaN overlayer grown on ion beam modified Si(111) have been investigated. Si(111) surface was treated RIB with 1KeV-N$_2$$\^$+/(at 1.9 ${\times}$ 10$\^$-5/) to dose ranging from 5${\times}$10$\^$15/ to 1${\times}$10$\^$17/ prior to film growth. GaN epilayers were grown at 1100$^{\circ}C$ for 1 hour after growing AlN buffer layers for 5∼30 minutes at 1100$^{\circ}C$ in Metal Organic Chemical Vapor Deposition (MOCVD). The properties of GaN epilayers were evaluated by X-Ray Diffraction(XRD), Raman spectroscopy, Photoluminescence(PL) and Hall measurement. The results showed that the ion modified treatment markedly affected to the structural, optical and electrical characteristic of GaN layers.

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Search for Adsorption Coordination of SiH4 or Al(CH3)3 on Si (001) Surface Using Genetic Algorithm and Density Functional theory (유전 알고리즘과 밀도 범함수 이론을 이용한 Si (001) 표면에서의 SiH4 또는 Al(CH3)3 전구체의 흡착 배위 탐색)

  • Kim, Hyun-Kyu;Kim, Jason;Kim, Yeong-Cheol
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.4
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    • pp.16-22
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    • 2021
  • We search for an appropriate initial adsorption coordination of precursor on surface by using genetic algorithm (GA) and density functional theory. SiH4 and Al(CH3)3 as precursor, and OH-terminated Si (001) as surface are used for this study. Selection, crossover, and mutation as hyperparameters of GA are applied to search for the adsorption coordination of the precursors on the surface as a function of generation. Bond distances between precursors and the surface are used to explain the adsorption behavior of the precursors.

The Effect of $N_2O$ treatment and Cap Oxide in the PECVD $SiO_xN_y$ Process for Anti-reflective Coating (ARC를 위한 PECVD $SiO_xN_y$ 공정에서 $N_2O$ 처리 및 cap 산화막의 영향)

  • Kim, Sang-Yong;Seo, Yong-Jin;Kim, Chang-Il;Chung, Hun-Sang;Lee, Woo-Sun;Chang, Eui-Goo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.04b
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    • pp.39-42
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    • 2000
  • As gate dimensions continue to shrink below $0.2{\mu}m$, improving CD (Critical Dimension) control has become a major challenge during CMOS process development. Anti-Reflective Coatings are widely used to overcome high substrate reflectivity at Deep UV wavelengths by canceling out these reflections. In this study, we have investigated Batchtype system for PECVO SiOxNy as Anti-Reflective Coatings. The Singletype system was baseline and Batchtype system was new process. The test structure of Singletype is SiON $250{\AA}$ + Cap Oxide $50{\AA}$ and Batchtype is SiON $250{\AA}$ + Cap Oxide $50{\AA}$ or N2O plasma treatment. Inorganic chemical vapor deposition SiOxNy layer has been qualified for bottom ARC on Poly+WSix layer, But, this test was practiced on the actual device structure of TiN/Al-Cu/TiN/Ti stacks. A former day, in Batchtype chamber thin oxide thickness control was difficult. In this test, Batchtype system is consist of six deposition station, and demanded 6th station plasma treatment kits for N2O treatment or Cap Oxide after SiON $250{\AA}$. Good reflectivity can be obtained by Cap Oxide rather than N2O plasma treatment and both system of PECVD SiOxNy ARC have good electrical properties.

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Characterization of Al2O3 Thin Film Encasulation by Plasma Assisted Spatial ALD Process for Organic Light Emitting Diodes

  • Yong, Sang Heon;Cho, Sung Min;Chung, Ho Kyoon;Chae, Heeyeop
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.234.2-234.2
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    • 2014
  • Organic light emitting diode (OLED) is considered as the next generation flat panel displays due to its advantages of low power consumption, fast response time, broad viewing angle and flexibility. For the flexible application, it is essential to develop thin film encapsulation (TFE) to protect oxidation of organic materials from oxidative species such as oxygen and water vapor [1]. In many TFE research, the inorganic film by atomic layer deposition (ALD) process demonstrated a good barrier property. However, extremely low throughput of ALD process is considered as a major weakness for industrial application. Recently, there has been developed a high throughput ALD, called 'spatial ALD' [2]. In spatial ALD, the precursors and reactant gases are supplied continuously in same chamber, but they are separated physically using a purge gas streams to prevent mixing of the precursors and reactant gases. In this study, the $Al_2O_3$ thin film was deposited by spatial ALD process. We characterized various process variables in the spatial ALD such as temperature, scanning speed, and chemical compositions. Water vapor transmission rate (WVTR) was determined by calcium resistance test and less than $10-^3g/m^2{\cdot}day$ was achieved. The samples were analyzed by x-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope (FE-SEM).

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Homogenization of Plastic Behavior of Metallic Particle/Epoxy Composite Adhesive for Cold Spray Deposition (저온 분사 공정을 위한 금속입자/에폭시 복합재료 접착제의 소성 거동의 균질화 기법 연구)

  • Yong-Jun Cho;Jae-An Jeon;Kinal Kim;Po-Lun Feng;Steven Nutt;Sang-Eui Lee
    • Composites Research
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    • v.36 no.3
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    • pp.199-204
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    • 2023
  • A combination of a metallic mesh and an adhesive layer of metallic particle/epoxy composite was introduced as an intermediate layer to enhance the adhesion between cold-sprayed particles and fiber-reinforced composites (FRCs). Aluminum was considered for both the metallic particles in the adhesive and the metallic mesh. To predict the mechanical characteristics of the intermediate bond layer under a high strain rate, the properties of the adhesive layer needed to be calculated or measured. Therefore, in this study, the Al particle/epoxy adhesive was homogenized by using a rule of mixture. To verify the homogenization, the penetration depth, and the thickness decrease after the cold spray deposition from the undeformed surface, was monitored with FE analysis and compared with experimental observation. The comparison displayed that the penetration depth was comparable to the diameters of one cold spray particle, and thus the homogenization approach can be reasonable for the prediction of the stress level of particulate polymer composite interlayer under a high strain rate for cold spray processing.

Planarization of SUS310 Metal Substrate Used for Coated Conductor Substrate by Chemical Solution Coating Method (화학적인 용액 코팅방법에 의한 박막형 고온초전도체에 사용되는 SUS310 금속모재의 평탄화 연구)

  • Lee, J.B.;Lee, H.J.;Kim, B.J.;Kwon, B.K.;Kim, S.J.;Lee, J.S.;Lee, C.Y.;Moon, S.H.;Lee, H.G.;Hong, G.W.
    • Progress in Superconductivity
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    • v.12 no.2
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    • pp.118-123
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    • 2011
  • The properties of $2^{nd}$ generation high temperature superconducting wire, coated conductor strongly depend on the quality of superconducting oxide layer and property of metal substrate is one of the most important factors affecting the quality of coated conductor. Good mechanical and chemical stability at high temperature are required to maintain the initial integrity during the various process steps required to deposit several layers consisting coated conductor. And substrate need to be nonmagnetic to reduce magnetization loss for ac application. Hastelloy and stainless steel are the most suitable alloys for metal substrate. One of the obstacles in using stainless steel as substrate for coated conductor is its difficulties in making smooth surface inevitable for depositing good IBAD layer. Conventional method involves several steps such as electro polishing, deposition of $Al_2O_3$ and $Y_2O_3$ before IBAD process. Chemical solution deposition method can simplify those steps into one step process having uniformity in large area. In this research, we tried to improve the surface roughness of stainless steel(SUS310). The precursor coating solution was synthesized by using yttrium complex. The viscosity of coating solution and heat treatment condition were optimized for smooth surface. A smooth amorphous $Y_2O_3$ thin film suitable for IBAD process was coated on SUS310 tape. The surface roughness was improved from 40nm to 1.8 nm by 4 coatings. The IBAD-MgO layer deposited on prepared substrate showed good in plane alignment(${\Delta}{\phi}$) of $6.2^{\circ}$.