• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.663-666
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• 2004

In this paper, we have investigated the structure and dielectric properties of the $(Ba_{0.6}Sr_{0.4})TiO_3$ (BST) thin films film fabricatedon MgO(100)/Si substrate by an alkoxide-based sol-gel method. Both the structure and morphology of films were analyzed by x-ray diffraction (XRD) and atomic force microscope (AFM). For the MgO(100)/Si substrates, the BST thin films exhibited highly (100) orientation. The highly (100)-oriented BST thin films showed high dielectric constant, tunability, and figure of merit (FOM). The dielectric constants, dielectric loss and tunability of the BST thin films annealed at 700 C deposited on the MgO(100)/Si substrates measured at 10 kHz were 515.9, 0.0082, and 54.3 %, respectively.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.63-69
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• 1999

The electrical properties of rf-magnetron sputtered $Ba_{0.5}Sr_{0.3}TiO_3$ (BST) capacitors were investigated by varying annealing temperature and atmosphere of the rapid thermal annealing (RTA). The electrical properties of Pt/BST/Pt capacitors were found to strongly depend on the RTA condition. It seems that the dependence of the electrical properties of the Pt/BST/Pt capacitors on the RTA condition is related to the oxygen vacancies in BST thin films. In order to clarify the relation between the oxygen vacancies and the electrical properties of Pt/BST/Pt capacitors, we have examined the two different annealing methods. One annealing method was performed in $O_2$ gas and the other was done in $O_2$-plasma at the same condition of 450$^{\circ}C$, 20 mtorr. It was found that the leakage current densities of $O_2$-plasma annealed capacitor were much lower than those of $O_2$ annealed capacitor. The dielectric constants of $O_2$ annealed capacitor decreased about 14% comparing with those of as-deposited. In contrast, there was no decrease in the dielectric constant of $O_2$-plasma annealed. These results indicate that $O_2$-plasma annealing is very effective in compensation the oxygen vacancies in BST thin films. It can be also concluded that the oxygen vacancies greatly affect the electrical properties of Pt/BST/Pt capacitors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.197-198
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• 2005

본 논문에서는 p-type (100)Si. (100)MgO 그리고 MgO/Si 기판 위에 RF Magnetron sputtering 법으로 $Ba_{0.5}Sr_{0.5}TiO_3$(BST) 박막을 증착 후 $600^{\circ}C$ 의 질소분위에서 RTA(Rapid Thermal Annealing)를 이용한 1 분간의 고온 급속열처리를 하였다. XRD 측정결과 모든 기판에서 (110) $Ba_{0.5}Sr_{0.5}TiO_3$의 주피크가 관찰되어졌고, 열처리 후 피크 세기가 증가함을 확인할 수 있었다. C-V 특성에서 각각의 기판에서 측정된 커패시턴스 값으로 계산된 유전율은 120(bare Si), 305(MgO/Si) 그리고 310(MgO)이었다. 누설 전류 특성에서는 150KV/cm이내의 인가전계에서 0.1$uA/cm^2$이하의 안정된 누설전류값을 보여주었다. 결론적으로 MgO 버퍼층을 이용한 기판이 BST 박막의 증착을 위한 기판으로써 효과적임을 알 수 있었다.

• Journal of the Korean Vacuum Society
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• v.9 no.3
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• pp.242-248
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• 2000

BST thin films were prepared with various deposition conditions by rf-magnetron sputtering. As substrate temperature increases and Ar/$O_2$ratio decreases, the electrical properties of the BST films improve. The conventional Schottky model and modified-Schottky model were introduced in order to investigate the leakage-current-conduction mechanisms of the deposited films. It was found that the modified-Schottky model better describes the current-conduction mechanism in the BST films than the conventional Schottky model. From the modified-Schottky model, optical dielectric constant ($\varepsilon$), electronic drift mobility ($\mu$), and barrier height $({\phi}_b)are calculated as $\varepsilon$=4.9, $\mu$=0.019 $\textrm{cm}^2$/V-s, and ${\phi}_b=0.79 eV.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.8-8
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• 1994

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.10a
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• pp.67-67
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• 1997

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.10-13
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• 2002

본 논문에서는 P-type (100)Si 기판위에 RF magnetron sputtering법으로 강유전체 BST 박막을 증착하기 위한 완충층용(buffer layer) MgO 박막을 제작하였다. 증착 시 기판온도는 $400^{\circ}C$, 작업가스 Ar:$O_2$:=80:20, 작업진공 10m torr에서 RF 파워를 25W, 50W, 7SW로 변화하면서 증착하여 최적의 RF 파워조건을 확립하였다. XRD 측정결과 RF 파워 세기에 관계없이 MgO(200)피크만 관찰되었고 RF 파워 5OW에서 제작한 박막이 가장 양호한 결정성을 나타내었고 이 때 I-V측정결과 $\pm$ 1.5 MV/$cm^2$에서 $10^{-7}$A/$cm^2$이하의 양호한 누설전류특성을 나타내었고 C-V 측정결과 히스테리시스가 거의없는 양호한 인터페이스 특성을 보여주었고 비유전율은 약 8.4였다.

• 한국ITS학회:학술대회논문집
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• 2004.11a
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• pp.311-314
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• 2004

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.11a
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• pp.53-53
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• 1996

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.9
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• pp.711-717
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• 1998

BST(70/30) and BST(50/50) thin films were prepared by Sol-Gel method and studied about the microstructural and dielectric properties with Pt and ITO bottom electrodes. The stock solution was synthesized and spin coated on the Pt/Ti$SiO_2$/Si and Indium Tin Oxide(ITO)/ glass substrate. the coated films were dries at 350$^{\circ}C$ for 10 minutes and annealed at $750^{\circ}C$ for 1 hour for the crystallization. The thin films coated on ITO substrate were crystallized easily and the packing density and roughness of surface were better that those of films coated on Pt substrates. In the BST(50/50) composition the structural properties were similar to the BST(70/30) composition and grain size were decreased with increasing the contents of Sr. The dielectric constant was higher in the BST(50/50) composition compared with the BST(70/30) composition. Using the ITO substrate, the dielectric constant was higher than the Pt substrate while the dielectric loss was showed a reverse trend. The dielectric constant with and increase of temperature was decreased slowly.