TiO2-x films for bolometer applications: recent progress and perspectives

The bolometer is widely used in military and civilian infrared imaging due to its advantages of non-cooling, small size and portability. Thermosensitive materials seriously affect the performance of bolometers. As a kind of heat-sensitive material, the TiO2-x material has the advantages of good thermal stability, large-area preparation, and compatibility with the complementary metal-oxide semiconductor (CMOS) process. However, there is almost no review on the application of titanium oxide for bolometers. In this paper, we introduce the bolometer's main thermal and photoelectric performance parameters and the critical technologies to manufacture the bolometer. Finally, we will particularly emphasize the effects of preparation process parameters of TiO2 on the performance parameters temperature coefficient of resistance (TCR), 1/f noise, etc., were studied.

Temperature resistance coefficient of doped with rare earth elements nanostructured silicon films

The regularities of changes in the concentration of an electrically active dopant in a nanostructured silicon film by changing the electrical resistivity depending on the doping conditions were investigated. The dependences of the changes in the obtained structures doped with rare-earth elements, such as La, Eu, Sm, Dy, Gd (lanthanides), on nanostructured silicon films are determined. The regularities of the obtained films changes and the temperature coefficient of resistance (TCR) change depending on the formation conditions are established. The regularities of the TCR are shown depending on the selected conditions for doping or non-doping of nanostructured silicon films with various impurities. It is shown that the main conditions under which the effect and change in the temperature coefficient of resistors resistance on thin films using rare-earth elements, such as oxygen, boron and phosphorus in the bulk of the film, is considered to be the temperature effect after deposition.

Electron Conduction Processes in Tantalum-Germanium Multilayers

<p>An explosion of both theoretical and experimental research into structurally disordered materials in the late 1970s has greatly increased our understanding of these complex systems. A number of facets of the conduction processes remain unexplained, however, particularly in the area of non-simple metals. Multilayers of disordered tantalum and amorphous germanium with individual layer thicknesses of between 4 & 120A [Angstrom] and 13 & 220A [Angstrom]respectively have been prepared by vapour deposition and the in-plane resistance measured from 1.5 to 300K. Results for samples with germanium layers of sufficient thickness to prevent tunnelling between the conducting tantalum layers can be interpreted in terms of conduction in the tantalum layers alone. In these samples the behaviour of the resistance as a function of temperature and the tantalum layer thickness can be explained in terms of the interplay between quantum interference effects and disorder enhanced electron-electron interaction effects. At high temperatures the negative temperature coefficient of resistance arises from the destruction of coherent interference in the backscattered direction by phonons. From the data, the electron-phonon scattering rate is found to be comparable in magnitude to that expected for scattering in either the "clean" or "dirty" limits while the temperature dependence of the scattering rate lies between that expected for each of these limits. At lower temperatures a turn over to a positive temperature coefficient of resistance is seen as spin-orbit scattering and superconducting fluctuations become important. At still lower temperatures the resistance is dominated by electron-electron interaction effects and we have observed a transition from three-dimensional to two-dimensional behaviour as the tantalum layer thickness is reduced. Evidence for the onset of superconductivity is seen for samples with a low temperature sheet resistance of less than 3000 Omega/whitesquare. We have also investigated samples with thin germanium layers (<40A [Angstrom]) in which coupling between the layers causes an increase in the superconducting transition temperature. We present some preliminary measurements which suggest that the transition from isolated to coupled tantalum layers, as the germanium layer thickness is reduced, can be followed in the form of the fluctuation conductivity.</p>

Electron Conduction Processes in Tantalum-Germanium Multilayers

<p>An explosion of both theoretical and experimental research into structurally disordered materials in the late 1970s has greatly increased our understanding of these complex systems. A number of facets of the conduction processes remain unexplained, however, particularly in the area of non-simple metals. Multilayers of disordered tantalum and amorphous germanium with individual layer thicknesses of between 4 & 120A [Angstrom] and 13 & 220A [Angstrom]respectively have been prepared by vapour deposition and the in-plane resistance measured from 1.5 to 300K. Results for samples with germanium layers of sufficient thickness to prevent tunnelling between the conducting tantalum layers can be interpreted in terms of conduction in the tantalum layers alone. In these samples the behaviour of the resistance as a function of temperature and the tantalum layer thickness can be explained in terms of the interplay between quantum interference effects and disorder enhanced electron-electron interaction effects. At high temperatures the negative temperature coefficient of resistance arises from the destruction of coherent interference in the backscattered direction by phonons. From the data, the electron-phonon scattering rate is found to be comparable in magnitude to that expected for scattering in either the "clean" or "dirty" limits while the temperature dependence of the scattering rate lies between that expected for each of these limits. At lower temperatures a turn over to a positive temperature coefficient of resistance is seen as spin-orbit scattering and superconducting fluctuations become important. At still lower temperatures the resistance is dominated by electron-electron interaction effects and we have observed a transition from three-dimensional to two-dimensional behaviour as the tantalum layer thickness is reduced. Evidence for the onset of superconductivity is seen for samples with a low temperature sheet resistance of less than 3000 Omega/whitesquare. We have also investigated samples with thin germanium layers (<40A [Angstrom]) in which coupling between the layers causes an increase in the superconducting transition temperature. We present some preliminary measurements which suggest that the transition from isolated to coupled tantalum layers, as the germanium layer thickness is reduced, can be followed in the form of the fluctuation conductivity.</p>

Noise Improvement of a-Si Microbolometers by the Post-Metal Annealing Process

To realize high-resolution thermal images with high quality, it is essential to improve the noise characteristics of the widely adopted uncooled microbolometers. In this work, we applied the post-metal annealing (PMA) process under the condition of deuterium forming gas, at 10 atm and 300 °C for 30 min, to reduce the noise level of amorphous-Si microbolometers. Here, the DC and temperature coefficient of resistance (TCR) measurements of the devices as well as 1/f noise analysis were performed before and after the PMA treatment, while changing the width of the resistance layer of the microbolometers with 35 μm or 12 μm pixel. As a result, the microbolometers treated by the PMA process show the decrease in resistance by about 60% and the increase in TCR value up to 48.2% at 10 Hz, as compared to the reference device. Moreover, it is observed that the noise characteristics are improved in inverse proportion to the width of the resistance layer. This improvement is attributed to the cured poly-silicon grain boundary through the hydrogen passivation by heat and deuterium atoms applied during the PMA, which leads to the uniform current path inside the pixel.

Computer‐aided selective production of low-resistance NiP and NiCuP layers

Purpose This paper aims to present the possibility of computer-aided technology of chemical metallization for the production of electrodes and resistors based on Ni-P and Ni-Cu-P layers. Design/methodology/approach Based on the calculated parameters of the process, test structures were made on an alumina substrate using the selective metallization method. Dependences of the surface resistance on the metallization time were made. These dependencies take into account the comparison of the calculations with the performed experiment. Findings The author created a convenient and easy-to-use tool for calculating basic Ni-P and Ni-Cu-P layer parameters, namely, surface resistance and temperature coefficient of resistance (TCR) of test resistor, based on chemical metallization parameters. The values are calculated for a given level of surface resistance of Ni-P and Ni-Cu-P layer and defined required range of changes of TCR of test resistor. The calculations are possible for surface resistance values in the range of 0.4 Ohm/square ÷ 2.5 Ohm/square. As a result of the experiment, surface resistances were obtained that practically coincide with the calculations made with the use of the program created by the authors. The quality of the structures made is very good. Originality/value To the best of the authors’ knowledge, the paper presents a new, unpublished method of manufacturing electrodes (resistors) on silicon, Al2O3 and low temperature co-fired ceramic substrates based on the authors developed computer program.