• 한국전기전자재료학회논문지
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• 제18권6호
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• pp.554-559
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• 2005

Ni/Cr thin film is very interesting material as thin film resistors, filaments, and humidity sensors because their relatively large resistivity, more resistant to oxidation and a low temperature coefficient of resistance (TCR). These interesting properties of Ni/Cr thin films are dependent upon the preparation conditions including the deposition environment and subsequent annealing treatments. Ni/Cr thin films of 250 nm were deposited by DC magnetron sputtering on $Al_2O_3/Si$ substrate with 2-inch Ni/Cr (80/20) alloy target at room temperature for 45 minutes. Annealing treatments were performed at $400^{\circ}C,\;500^{\circ}C,\;and\;600^{\circ}C$ for 6 hours in air or $H_2$ ambient, respectively. The clear crystal boundaries without crystal growth and the densification were accomplished when the pores were disappeared in air ambient. Most of surface was oxidic including NiO, $Ni_2O_3$ and $Cr_xO_y$(x=1,2, y=2,3) after annealing in air ambient. The crystal growth in $H_2$ ambient was formed and stabilized by combination with each other due to the suppression of oxidized substance on film surface. Most oxidic Ni was restored when the oxidic Cr was present due to its stability in high-temperature $H_2$ ambient.

• 한국결정성장학회지
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• 제13권6호
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• pp.297-303
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• 2003

rf magnetron sputtering법을 이용하여 Mn-Ni-Co계 써미스터 박막을 증착하였다. $300^{\circ}C$ 및 $Ar/O_2$ = 10/0에서, cubic spinel 상형성이 이루어졌으며 공정가스에 산소 첨가 시, cubic spinel 상은 열처리를 통해서도 형성되지 않았다. 써미스터 박막은 Mn, Ni, Co 성분 외 다른 이종 성분은 포함되어 있지 않았다. 써미스터 박막에 대한 적외선 반사 특성을 분석으로 증착된 박막은 일정 각도로 입사되는 적외선에 대해 비교적 높은 반사율을 가짐을 관찰할 수 있었다. DI water : $HNO_3$: HCI=60 : 30 : 10 vo1%에서 써미스터 박막의 식각 속도는 약 63 nm/min였다. 박막 써미스터의 B상수는 약 3500 K였으며 TCR은 약 -3.95%/K였다 전압감도는 약 108.5 V/W였으며 NEP와 specific detectivity는 각각 $5.1\times 10^{-7}$ W/$Hz^{-1/2}$ $0.2\times 10^6$cm $Hz^{1/2}$/W였다.

• 한국전기전자재료학회논문지
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• 제36권3호
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• pp.249-254
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• 2023

La_0.7-xCe_xSr_0.3MnO₃ specimens were fabricated by a solid state reaction method and structural and electrical properties with variation of Ce⁴⁺ contents were measured. All specimens exhibited a polycrystalline rhombohedral crystal structure, and the (110) peaks were shifted to low angle side with increasing the amount of Ce⁴⁺ contents. As Ce⁴⁺ ions with different ion radii and charges are substituted with La³⁺ ions, electrical properties are thought to be affected by changes in the double exchange interaction between Mn³⁺-Mn⁴⁺ ions due to distortion of the unit lattice, a decrease in oxygen vacancy concentration, and an increase in lattice defects. Resistivity gradually decrease as the amount of Ce⁴⁺ added increased, and negative temperature coefficient of resistance (NTCR) properties were shown in all specimens. In the La_0.5Ce_0.2Sr_0.3MnO₃ specimens, electrical resistivity, TCR and B-value were 31.8 Ω-cm, 0.55%/℃ and 605 K, respectively.

• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.292-296
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• 2022

(La_0.5Nd_0.2Sr_0.3)MnO₃ specimens were prepared by a solid-state reaction. In all specimens, X-ray diffraction patterns of an orthorhombic structure were shown. The fracture surfaces of (La_0.5Nd_0.2Sr_0.3)MnO₃ specimens showed a transgranular fracture pattern be possibly due to La ions (0.122 nm) as a perovskite A-site dopant substituting for Nd ions (0.115 nm) having a small ionic radius. The full-width at half maximum (FWHM) of the Mn 2p XPS spectra showed a value greater than that [8] of the single valence state, which is believed to be due to the overlapping of Mn²⁺, Mn³⁺, and Mn⁴⁺ ions. The dependence of Mn 2p spectra on the Mn³⁺/Mn⁴⁺ ratio according to sintering time was not observed. Electrical resistivity resulted in the minimum value of 100.7 Ω-cm for the specimen sintered for 9 hours. All specimens show a typical negative temperature coefficient of resistance (NTCR) characteristics. In the 9-hour sintered specimen, TCR, activation energy, and B25/65-value were -1.24%/℃, 0.19 eV, and 2,445 K, respectively.