• Title/Summary/Keyword: aluminum nitride

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AlN Based RF MEMS Tunable Capacitor with Air-Suspended Electrode with Two Stages

  • Cheon, Seong J.;Jang, Woo J.;Park, Hyeon S.;Yoon, Min K.;Park, Jae Y.
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.13 no.1
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    • pp.15-21
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    • 2013
  • In this paper, a MEMS tunable capacitor was successfully designed and fabricated using an aluminum nitride film and a gold suspended membrane with two air gap structure for commercial RF applications. Unlike conventional two-parallel-plate tunable capacitors, the proposed tunable capacitor consists of one air suspended top electrode and two fixed bottom electrodes. One fixed and the top movable electrodes form a variable capacitor, while the other one provides necessary electrostatic actuation. The fabricated tunable capacitor exhibited a capacitance tuning range of 375% at 2 GHz, exceeding the theoretical limit of conventional two-parallel-plate tunable capacitors. In case of the contact state, the maximal quality factor was approximately 25 at 1.5 GHz. The developed fabrication process is also compatible with the existing standard IC (integrated circuit) technology, which makes it suitable for on chip intelligent transceivers and radios.

Effect of nitrogen concentration on the microstructures of AlN thin films fabricated by reactive RF sputtering (반응성 RF 마그네트론 스퍼터링으로 증착한 AlN 박막의 특성에 질소농도 변화가 미치는 영향)

  • Lim, Dong-Ki;Kim, Byoung-Kyun;Jeong, S.W.;Roh, Yong-Han
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.367-367
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    • 2008
  • Aluminum nitride (AlN) thin films have been deposited on Si substrate by using reactive RF magnetron sputtering method in a gas mixture of Ar and $N_2$ at different $N_2$ concentration. It was found that $N_2$ concentration was varied in the range up to 20-100%, highly c-axis oriented film can be obtained at 50% $N_2$ with full width at half maximum (FWHM) $4.5^{\circ}$. Decrease in surface roughness from 7.5 nm to 4.6 nm found to be associated with decrease in grain size, with $N_2$ concentration; however, the AlN film fabricated at 20% $N_2$ exhibited a granular type of structure with non-uniform grains. The absorption peak was observed around 675 $cm^{-1}$ in fourier transform infrared spectroscopy (FTIR). It is concluded that the AlN film deposited at $N_2$ concentration of 50% exhibited the most desirable properties for the application of high-frequency surface acoustic devices.

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Influence of Residual Oxygen on the growth of AlN Thin Films with Substrate Temperature (기판 온도 변화에 따른 AlN 박막 성장에 잔류 산소가 미치는 영향)

  • Kim, Byoung-Kyun;Lee, Eul-Tack;Kim, Eung-Kwon;Jeong, Seok-Won;Roh, Yong-Han
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.5
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    • pp.463-467
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    • 2008
  • Aluminum nitride (AlN) thin films have been deposited on Au electrodes by using reactive RF magnetron sputtering method in a gas mixture of Ar and $N_2$ at different substrate temperature. It was found that substrate temperature was varied in the range up to $400^{\circ}C$, highly c-axis oriented film can be obtained at $300^{\circ}C$ with full width at half maximum (FWHM) $3.1^{\circ}$. Increase in surface roughness from 3.8 nm to 5.9 nm found to be associated with increase in grain size, with substrate temperature; however, the AlN film fabricated at $400^{\circ}C$ exhibited a granular type of structure with non-uniform grains. The Al 2p and N 1s peak in the X-ray photoelectron spectroscopy (XPS) spectrum confirmed the formation of Al-N bonds. The XPS spectrum also indicated the presence of oxynitrides and oxides, resulting from the presence of residual oxygen in the vacuum chamber. It is concluded that the AlN film deposited at substrate temperature of $300^{\circ}C$ exhibited the most desirable properties for the application of high-frequency surface acoustic devices.

Investigation of Initial Formation of Aluminum Nitride Films by Single Precursor Organometallic Chemical Vapor Deposition of$[Me_{2}Al(\mu-NHR)]_{2}\;(R=^{i}Pr,\;^{t}Bu)$

  • Sung Myung Mo;Jung Hyun Dam;Lee June-Key;Kim Sehun;Park Joon T.;Kim Yunsoo
    • Bulletin of the Korean Chemical Society
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    • v.15 no.1
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    • pp.79-83
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    • 1994
  • The organometallic chemical vapor deposition of single precursors, $[Me_2Al({\mu}-NHR)]_2\;(R=^iPr,\;^tBu)$, for alumininum nitride thin films has been investigated to evaluate their poroperties as potential precursors. In chemical vapor deposition processes the gas phase products scattered from a Ni(100) substrate were analyzed by mass spectrometry and the deposited films were characterized by X-ray photoelectron spectroscopy (XPS). The optimum temperatures for the formation of AlN films have been found to be between 700 K and 800 K. Carbon contamination of the films seems to be attributed mainly to the methyl groups bonded to the aluminum atoms. It is apparent that $^tBu$ group is better than $^iPr$ group as a substituent on the nitrogen atom of the single precursors for the AlN thin film formation.

Research of aluminum nitride water load for the 4.6 GHz 500 kW LHCD system of the CFETR

  • Dingzhen Li;Liyuan Zhang;Lianmin Zhao;Fukun Liu;Min Cheng;Huaichuan Hu;Taian Zhou
    • Nuclear Engineering and Technology
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    • v.55 no.9
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    • pp.3126-3132
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    • 2023
  • To meet the increasing heating needs of the China Fusion Experimental Tokamak Reactor (CFETR), the output power in each Lower Hybrid Current Drive (LHCD) transmission line should be increased from 250 kW to 500 kW. Therefore, a new high-power water load must be developed for the 4.6 GHz 500 kW LHCD system. This paper aims to report the most recent research progress of the water load: aluminum nitride (AlN) ceramic is used as the media material to isolate the water and vacuum, and the radio frequency (RF) simulation results show that the return loss of the water load is less than -25dB at 4.6 GHz over a wide temperature range. Under 500 kW continuous wave (CW) operation, the maximum temperatures of the ceramic and water are separately 67 ℃ and 62 ℃, resulting in thermal deformation of the ceramic of approximately 0.003 mm. Moreover, the AlN water load was tested on the 4.6 GHz 250 kW high-power test bench and found to work well with low reflected power.

Surface Analysis of Plasma Pretreated Sapphire Substrate for Aluminum Nitride Buffer Layer

  • Jeong, Woo Seop;Kim, Dae-Sik;Cho, Seung Hee;Kim, Chul;Jhin, Junggeun;Byun, Dongjin
    • Korean Journal of Materials Research
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    • v.27 no.12
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    • pp.699-704
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    • 2017
  • Recently, the use of an aluminum nitride(AlN) buffer layer has been actively studied for fabricating a high quality gallium nitride(GaN) template for high efficiency Light Emitting Diode(LED) production. We confirmed that AlN deposition after $N_2$ plasma treatment of the substrate has a positive influence on GaN epitaxial growth. In this study, $N_2$ plasma treatment was performed on a commercial patterned sapphire substrate by RF magnetron sputtering equipment. GaN was grown by metal organic chemical vapor deposition(MOCVD). The surface treated with $N_2$ plasma was analyzed by x-ray photoelectron spectroscopy(XPS) to determine the binding energy. The XPS results indicated the surface was changed from $Al_2O_3$ to AlN and AlON, and we confirmed that the thickness of the pretreated layer was about 1 nm using high resolution transmission electron microscopy(HR-TEM). The AlN buffer layer deposited on the grown pretreated layer had lower crystallinity than the as-treated PSS. Therefore, the surface $N_2$ plasma treatment on PSS resulted in a reduction in the crystallinity of the AlN buffer layer, which can improve the epitaxial growth quality of the GaN template.

Growth of Aluminum Nitride Thin Films by Atomic Layer Deposition and Their Applications: A Review (원자층 증착법을 이용한 AlN 박막의 성장 및 응용 동향)

  • Yun, Hee Ju;Kim, Hogyoung;Choi, Byung Joon
    • Korean Journal of Materials Research
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    • v.29 no.9
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    • pp.567-577
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    • 2019
  • Aluminum nitride (AlN) has versatile and intriguing properties, such as wide direct bandgap, high thermal conductivity, good thermal and chemical stability, and various functionalities. Due to these properties, AlN thin films have been applied in various fields. However, AlN thin films are usually deposited by high temperature processes like chemical vapor deposition. To further enlarge the application of AlN films, atomic layer deposition (ALD) has been studied as a method of AlN thin film deposition at low temperature. In this mini review paper, we summarize the results of recent studies on AlN film grown by thermal and plasma enhanced ALD in terms of processing temperature, precursor type, reactant gas, and plasma source. Thermal ALD can grow AlN thin films at a wafer temperature of $150{\sim}550^{\circ}C$ with alkyl/amine or chloride precursors. Due to the low reactivity with $NH_3$ reactant gas, relatively high growth temperature and narrow window are reported. On the other hand, PEALD has an advantage of low temperature process, while crystallinity and defect level in the film are dependent on the plasma source. Lastly, we also introduce examples of application of ALD-grown AlN films in electronics.

Adhesive Behaviors of the Aluminum Alloy-Based CrN and TiN Coating Films for Ocean Plant

  • Murakami, Ri-Ichi;Yahya, Syed Qamma Bin
    • International Journal of Ocean System Engineering
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    • v.2 no.2
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    • pp.106-115
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    • 2012
  • In the present study, TiN and CrN films were coated by arc ion plating equipment onto aluminum alloy substrate, A2024. The film thickness was about 4.65 ${\mu}m$. TiN and CrN films were analyzed by X-ray diffraction and energy dispersive X-ray equipments. The Young's modulus and the micro-Vickers hardness of aluminum substrate were modified by the ceramic film coatings. The difference in Young's modulus between substrate and coating film would affect on the wear resistance. The critical load, Lc, was 75.8 N for TiN and 85.5 N for CrN. It indicated from the observation of optical micrographs for TiN and CrN films that lots of cracks widely propagated toward the both sides of scratch track in the early stage of MODE I. TiN film began to delaminate completely at MODE II stage. The substrate was finally glittered at MODE III stage. For CrN film, a few crack can be observed at MODE I stage. The delamination of film was not still occurred at MODE II and then was happened at MODE III. This agrees with critical load measurement which the adhesive strength was greater for CrN film than for TiN film. Consequently, it was difficult for CrN to delaminate because the adhesive strength was excellent against Al substrate. The wear process, which the film adheres and the ball transfers, could be enhanced because of the increase in loading. The wear weight of ball was less for CrN than for TiN. This means that the wear damage of ball was greater for TiN than for CrN film. It is also obvious that it was difficult to delaminate because the CrN coating film has high toughness. The coefficient of friction was less for CrN coating film than for TiN film.

High Temperature Stability of Nitride Ceramic Materials in LiF-NdF3-Nd2O3 Molten Salts System (LiF-NdF3-Nd2O3 용융염에서 질화물계 세라믹재료의 고온안정성)

  • Kwon, Sukcheol;Lee, Young-Jun;Ryu, Hong-Youl;Lee, Go Gi;Jo, Sung Koo;Lee, Jong-Hyeon
    • Korean Journal of Materials Research
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    • v.25 no.12
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    • pp.694-702
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    • 2015
  • Nd-Fe-B permanent magnets have been used in a wide variety of applications because of their high magnetic flux density. So, demand for neodymium has been increasing in worldwide. In this study, an electrowinning process was performed in $LiF-NdF_3-Nd_2O_3$ high temperature molten salts. However, a corrosion resistant material for use in the molten salt must be found for stable operation because of the harsh corrosion environment of the electrowinning process. Therefore, for this paper, boron nitride(BN), aluminum nitride(AlN), and silicon nitride($Si_3N_4$) were selected as protective and structural materials in the high temperature electrolyte. To investigate the characteristics of BN, AlN, and $Si_3N_4$, in molten salts, materials were immersed in the molten salts for 24, 72, 120, and 192 hours. Also, surface condition and stability were investigated by SEM and EDS and corrosion products were calculated by HSC chemistry. As a result, among BN, AlN, and $Si_3N_4$, AlN was found to show the best protective material properties.

Composite Coating of Nickel-Boron Nitride-Phosphours and Nickel-Boron Nitride-Boron Ternary System on Aluminum (알루미늄에 니켈-질화붕소-인과 니켈-질화붕소-붕소의 3원계 복합도금)

  • Kuak Woo-Sup;Yoon, Byung-Ha;Kim, Dai-Ryong
    • Journal of the Korean institute of surface engineering
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    • v.19 no.3
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    • pp.83-91
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    • 1986
  • Codeposited of boron nitride(BN) particle dispersed into electroless nickel-phosphours (Ni-P) and nickel-boron(Ni-B) platings were studied for the purpose of developing the wear resistance and lubricity. BN can be codeposited from electroless nickel plating bath with $NaH_2PO_2$ and $NaBH_4$ as the reducing agents. Most dispersolids were distributed uniformly in the Ni-P and Ni-B matrix. Abrasion loss decreased with increasing amount of codeposits and reached a constant value 2.4 percent by volume percent of BN particle. The wear resistance and the friction coefficient of the heat treated BN composite coatings were improved about three times than that of as-coatings. The BN composite coatings were more wear resistance than hard chromium. Ni-B-BN composite coatings showed lower wear resistance and friction coefficient than Ni-P-BN. The BN content of the deposite was found to be 2.4 v/o for these optium conditions.

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