Effects of pH value and deposition time on the electrical properties of (NMC) Ni-Mn-Cu-O and (NMCC) Ni-Mn-Cu-Co-O thin films were investigated. The NMC and NMCC films were prepared by spin spray method. The crystal structure and thickness of the annealed films were changed by the pH value and deposition time, respectively. A single phase of cubic spinel structure was confirmed for the annealed films deposited from solutions with pH 7.6. The resistivity of the annealed films was affected by the crystal structure and microstructure. The TCR (temperature coefficient of resistance) was dependent on the Mn3+/Mn4+. Typically, the resistivity of 70.5 Ω · ㎝ and TCR of -3.56%/K at room temperature were obtained for NMCC films deposited from solutions with pH 7.6 for 5 min, and annealed at 450℃ for 3 h.
Spinel thin films were prepared by the spin spray technique to develop new thermal imaging materials annealed at low temperature for uncooled microbolometer applications. The spinel thin films were deposited from [(Ni0.30Co0.33Mn0.37)1-xCux]3O4 (0.1≤x≤0.2) solutions and then annealed at 400℃ for 1 h inargon. Effects of Cu content (x) and deposition time on the electrical properties of the annealed films were investigated. With increasing deposition time, the resistivity of the annealed films increased. For the annealed films deposited for 1 min, the resistivity of x=0.15 films was lower than that of x=0.1 films due to the different grain sizes. The high temperature coefficient of resistance (TCR) of the annealed films could be obtained at temperature below 50℃. Typically, the resistivity of 127 Ω·cm and TCR of -5.69%/Kat 30℃ were obtained for x=0.1 films with deposition time of 1 min annealed at 400℃ for 1 h in argon.
[(Co1-xCux)0.2(Ni0.3Mn0.7)0.8]3O4 (0≤x≤1) thin films prepared by metal organic decomposition process were fabricated on SiN/Si substrate for infrared sensor application. Their structural and electrical properties were investigated with variation of Cu dopant. The [(Co1-xCux)0.2(Ni0.3Mn0.7)0.8]3O4 (CCNMO) film annealed at500℃ exhibited a dense microstructure and a homogeneous crystal structure with a cubic spinel phase. Theircrystallinity was further enhanced with increasing doped Cu amount. The 120 nm-thick CCNMO (x=0.6) thin film had a low resistivity of 53 Ω·cm at room temperature while the Co-free film (x=1) showed a significantly decreased resistivity of 5.9 Ω·cm. Furthermore, the negative temperature coefficient of resistance(NTCR) characteristics were lower than -2%/℃ for all the specimens with x≥0.6. These results imply that the CCNMO (x≥0.6) thin films are a good candidate material for infrared sensor application.
Copper manganite thin films were fabricated on SiNx/Si substrate by metal organic decomposition (MOD) process. They were burned-out at 400℃ and annealed at various temperatures (400∼800℃) for 1h in ambient atmosphere. Their micro-structure and negative temperature coefficient of resistance (NTCR) characteristics were analyzed for micro-bolometer application. The copper manganitefilm with a cubic spinel structure was well developed at 500℃ which confirmed by XRD and HRTEM analysis. It showed a low resistivity (47.5 Ω·cm) at room temperature and high NTCR characteristics of-4.12%/℃ and -2.15%/℃ at room temperature and 85℃, implying a good thin film for micro-bolometer application. Furthermore, its crystallinity was enhanced with increasing temperature to 600℃. However, the appearance of secondary phase at temperatures higher than 600℃ lead to deteriorate the NTCR characteristics.
Thin thermistor films of solutions with nickel and manganese oxides were prepared by metal-organic decomposition (MOD). The structural properties of the thin films were investigated as a function of annealing temperature. Field emission scanning electron microscope (FE-SEM) results indicated that the thin films had a thin thickness, smooth and dense surface. The crystallization temperature of 414.9℃ was confirmed from thermogavimetric-differential thermal analysis (TG-DTA)curve. A single phase of cubic spinel structure was obtained for the thin film annealed from 700℃ to 800℃,which was confirmed from the X-ray diffraction (XRD). From the selected area electron diffraction(SAED) in high resolution transmission electron microscope (HRTEM), the nano grains (2∼3 nm) of spinel phase with (311) and (222) planes were detected for the thin film annealed at 500℃, which could be applicable to read-out integrated circuit (ROIC) substrate of the uncooled microbolometer with low processing temperature.
In this paper, fabricated by MEMS uncooled micro-bolometer detector for the study in the infrared sensitivity enhancement. Absorption layer SiOx-Metal series MDTF (metal-dielectric thin film) by high absorption rate and has a high thermal coefficient of resistance, low noise characteristics were implemented. Then MDTF were made in a vacuum deposition method. And MDTF for the analysis of the physical properties of silicon wafers were fabricated, TCR (temperature coefficient of resistance) value was made in order to measure the glass wafer and FT-IR (Fourier Transform Infrared spectroscopy) values were made in order to measure the germanium window. The analyzed results of MDTF -3 [%/K] has more characteristics of the TCR. And 8∼12 um wavelength region close to 70% in the absorption characteristic.