• Journal of Sensor Science and Technology
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• v.14 no.1
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• pp.52-55
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• 2005

Ni oxide thin films with thermal sensitivity superior to Pt and Ni thin films were formed through annealing treatment after Ni thin films were deposited by a r.f. magnetron sputtering method. Resistivity values of Ni oxide thin films were in the range of $10.5{\mu}{\Omega}cm$ to $2.84{\times}10^{4}{\mu}{\Omega}cm$ according to the degree of Ni oxidation. Also temperature coefficient of resistance(TCR) values of Ni oxide thin films depended on the degree of Ni oxidation from 2,188 ppm/$^{\circ}C$ to 5,630 ppm/$^{\circ}C$ in the temperature range of $0{\sim}150^{\circ}C$. Because of the high linear TCR and resistivity characteristics, Ni oxide thin films exhibit much higher sensitivity to flow and temperature changes than pure Ni thin films and Pt thin films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.2
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• pp.169-173
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• 2005

Ni oxide thin films were formed through annealing treatment in the atmosphere after Ni thin films deposited by a r.f. magnetron sputtering method and then electric and material properties were analyzed for application to thermal sensors. Resistivity of Ni thin films decreased after annealing treatment at 30$0^{\circ}C$ and 40$0^{\circ}C$ for five hours due to crystallization of Ni thin films but the value increased over 45$0^{\circ}C$ because of Ni thin film's oxidation. Resistivity values of Ni thin films were in the range of 10.5 $\mu$Ωcm/$^{\circ}C$ to 2.84${\times}$10$^4$$\mu$Ωcm/$^{\circ}C$ according to the degree of Ni oxidation. Also temperature coefficient of resistance(TCR) values of Ni oxide thin films depended on the degree of Ni oxidation such as 2,188 ppm/$^{\circ}C$ to 5,630 ppm/$^{\circ}C$ in the temperature range of 0 $^{\circ}C$∼150 $^{\circ}C$. The results demonstrate that Ni oxide thin films of annealing treatment at 40$0^{\circ}C$ for 5hours could be more advantageous than pure Ni thin films and Pt thin films from a point of output properties and TCR, applied to thermal sensors.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.193.1-193.1
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• 2014

This study was to investigate the electronic structure and optical properties of Na doped into NiO thin film using XPS and REELS. The films were grown by electron beam evaporation with varying the annealing temperature. The relationship between the electrical characteristics with the local structure of NiO thin films was also discussed. The x-ray photoelectron results showed that the Ni 2p spectra for all films consist of Ni 2p3/2 which indicate the presence of Ni-O bond from NiO phase and for the annealed film at temperature above $200^{\circ}C$ shows the coexist Ni oxide and Ni metal phase. The reflection electron energy loss spectroscopy spectra showed that the band gaps of the NiO thin films were slightly decreased with Na-doped into films. The Na-doped NiO showed relatively low resistivity compared to the undoped NiO thin films. In addition, the Na-doped NiO thin films deposited at room temperature showed the best properties, such as a p-type semiconducting with low electrical resistivity of $11.57{\Omega}.cm$ and high optical transmittance of ~80% in the visible light region. These results indicate that the Na doping followed by annealing process plays a crucial in enhancing the electrical and optical properties of NiO thin films. We believe that our results can be a good guide for those growing NiO thin films with the purpose of device applications, which require deposited at room temperature.

• Journal of the Korean Electrochemical Society
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• v.14 no.3
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• pp.163-170
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• 2011

Nanocrystalline Ni thin films were electodeposited from chloride baths to investigate the influences of additive concentration, current density and solution pH on residual (or internal) stress, surface morphology, and microstructure of the films. It was observed that residual stress in Ni thin film was changed from tensile stress mode (about 150 MPa) to compressive stress mode (about -100 MPa) with increasing saccharin concentration as an additive. Microstructure of Ni thin films was changed with/without saccharin in baths. Ni thin films electrodeposited from saccharinfree bath mainly consisted of both FCC(111) and FCC(200) phases. However, Ni thin film electrodeposited from the baths containing saccharin exhibited FCC(111), FCC(200) and FCC (311) phases [sometimes, FCC (220)]. Current density influenced residual stress of Ni thin films. It was measured to be the lowest compressive stress value (about-100 MPa) in range of current density of $2.5\sim10mA{\cdot}cm^{-2}$. Solution pH also influenced residual stress of Ni thin film. Addition of saccharin in baths affected grain size of Ni thin films. Grain sizes of Ni thin films were measured to be about 60 nm without saccharin and 24~38 nm with more than 0.0005M saccharin concentration. Surface of Ni thin films was changed from nodular to smooth surface morphology with addition of saccharin.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.12
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• pp.1032-1038
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• 2000

Ni$_{81}$$Fe_{19}$(200 nm) thin films have been deposited by RF-magnetron sputtering on Si(001) substrates, Atomic force microscopy(AFM), X-ray diffraction(XRD) and magnetoresistance(MR) measurements of the thin films for investigating electromagnetic properties and microstructures were employed. During field annelaing for 1hr, there was no big difference n XRD patterns of Ni$_{81}$$Fe_{19}$ thin films. However, there was a significant change in XRD patterns of Ni$_{81}$$Fe_{19}$ thin films deposited at 40$0^{\circ}C$ during in-situ magnetic field deposition. The degree of surface roughness increased with increasing annealing and deposition temperature. With variation of surface roughness, there was no significant difference in MR Characteristics of Ni$_{18}$ $Fe_{19}$ thin films in 1hr-annealed case. High MR ratio was observed in the case of in-situ field deposited Ni$_{81}$$Fe_{19}$ films. 19/ films.

• Journal of Sensor Science and Technology
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• v.24 no.4
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• pp.224-227
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• 2015

In this study, 2 wt% Cr-doped Ni thin films were deposited using DC sputtering on a bare Si substrate using a 4 inch target at room temperature. In order to obtain ultrathin films from Cr-doped Ni thin films with high electrical properties and uniform surface, the micro-structure and electrical properties were investigated as a function of deposition time. For all deposition times, the Cr-doped Ni thin films had low average resistivity and small surface roughness. However, the resistivity of the Cr-doped Ni thin films at various ranges showed large differences for deposition times below 90 s. From the results, 120 s is considered as the appropriate deposition time for Cr-doped Ni thin films to obtain the lowest resistivity, a low surface roughness, and a small difference of resistivity. The Cr-doped Ni thin films are prospective materials for microdevices as ultrathin film electrodes.

• Journal of the Korean institute of surface engineering
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• v.51 no.1
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• pp.62-70
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• 2018

Sulfamate plating solution containing a small amount of chloride bath was fabricated to study the properties of the electrodeposited Ni thin films. Effects of the changes of current density and additive concentration on current efficiency, residual stress, surface morphology and microstructure of Ni thin films electrodeposited from Ni sulfamate-chloride baths were investigated. The current efficiency was measured to be more than about 95%, independent of the changes of current density and saccharin concentration in the baths. Residual stress of Ni thin film was appeared to be the compressive stress modes in the range of $5{\sim}30mA/cm^2$ current density. Maximum compressive stress was observed at the current density of $10mA/cm^2$. Compressive stress values of Ni thin/thick films were increased to be about -85~-100 MPa with increasing saccharin concentration from 0 to 0.0195 M(4 g/L). Surface morphology was changed from smooth to nodule surface appearance with increasing the current density. Smooth surface morphology of Ni thin films electrodeposited from the baths containing saccharin was observed, independent of the saccharin concentration. Ni thin/thick films consist of FCC(111), FCC(200), FCC(220), FCC(311) and FCC(222) peaks. It was revealed that the FCC(200) peak of Ni thin films is the preferred orientation in the range of $5{\sim}30mA/cm^2$ current density. The intensity of FCC(200) peak was gradually decreased and the intensity of FCC(111) peak was increased with increasing saccharin concentration in the baths.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.519-522
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• 2000

The correlation of surface morphology and magnetic property of NiFe thin films on Si(001) deposited by RF-magnetron sputter has been investigated, using AFM, XRD and MR measurements. During short field annealing for 15 min, there was no significant change in XRD patterns of NiFe thin films. However, the degree of surface roughness was changed with increasing annealing temperature. With variation of surface roughness, there was significant difference in MR characteristics of NiFe thin films. In the case of as-deposited NiFe thin films(T$\_$G/ = 150$^{\circ}C$) and UFA400 (T$\_$A/ = 400$^{\circ}C$) having smooth surface, good linearity of MR Curve was observed.

• Journal of the Korean Electrochemical Society
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• v.8 no.1
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• pp.32-36
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• 2005

[ $WO_3$ ] and $NiO-WO_3$ thin films were deposited on a Si (100) substrate by using high vacuum thermal evaporation. The effects of various film thicknesses on the surface morphology $WO_3$ and $NiO-WO_3$ thin films were investigated. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the deposited films. The results suggest that as $WO_3$ thin films became thick, their grain grew up to a $0.6{\mu}m$. On the other hand, NiO-doping to $WO_3$ thin films inhibited the grain growth five times less than undoped $WO_3$ thin films. This results show that NiO doping inhibited the grain growing of $WO_3$ thin films. Also, the variation of NOx sensitivity $(R_{NOx}/R_{air})$ to the thickness of $WO_3$ and $NiO-WO_3$ thin films were measured according to the thickness change of thin films and the working temperature of sensor in 5ppm NOx gas. As a result, $NiO-WO_3$ thin films showed more excellent properties than $WO_3$ thin films for NOx sensitivity.

• Journal of the Korean Vacuum Society
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• v.12 no.1
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• pp.16-19
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• 2003

Ni thin films on the p-InP (In) substrates were grown at room temperature by using the ion beam-assisted deposition. In order to determine the work function of the Ni thin films, the $\gamma$values were measured as functions of the acceleration voltages by using Ne, Ar, $N_2$. and Xe ion sources. The dependences of the values on various gases and on the acceleration voltages of the focused ion beam were obtained to determine the work function of the Ni thin films. The value of the work function of the Ni thin films grown on the p-InP (100) substrate was 5.8 eV ~ 5.85 eV. These results provide important information on the electronic properties of Ni thin films grown on p-InP (100) substrates at room temperature.