Elamaran Durgadevi, Akiba Ko, Satoh Hiroaki, Banerjee Amit, Hiromoto Norihisa, Inokawa Hiroshi
Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8011, Japan.
Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu 432-8561, Japan.
Nanomaterials (Basel). 2024 Jan 19;14(2):225. doi: 10.3390/nano14020225.
This study demonstrates the conversion of metallic titanium (Ti) to titanium oxide just by conducting electrical current through Ti thin film in vacuum and increasing the temperature by Joule heating. This led to the improvement of electrical and thermal properties of a microbolometer. A microbolometer with an integrated Ti thermistor and heater width of 2.7 µm and a length of 50 µm was fabricated for the current study. Constant-voltage stresses were applied to the thermistor wire to observe the effect of the Joule heating on its properties. Thermistor resistance 14 times the initial resistance was observed owing to the heating. A negative large temperature coefficient of resistance (TCR) of -0.32%/K was also observed owing to the treatment, leading to an improved responsivity of ~4.5 times from devices with untreated Ti thermistors. However, this does not improve the noise equivalent power (NEP), due to the increased flicker noise. Microstructural analyses with transmission electron microscopy (TEM), transmission electron diffraction (TED) and energy dispersive X-ray (EDX) confirm the formation of a titanium oxide (TiO) semiconducting phase on the Ti phase (85% purity) deposited initially, further to the heating. Formation of TiO during annealing could minimize the narrow width effect, which we reported previously in thin metal wires, leading to enhancement of responsivity.
本研究表明，仅通过在真空中对钛（Ti）薄膜施加电流并利用焦耳热升高温度，就能将金属钛转化为氧化钛。这使得微测辐射热计的电学和热学性能得到改善。为当前研究制作了一种集成了Ti热敏电阻且加热器宽度为2.7 µm、长度为50 µm的微测辐射热计。对热敏电阻丝施加恒压应力，以观察焦耳热对其性能的影响。由于加热，观察到热敏电阻的电阻约为初始电阻的14倍。由于该处理，还观察到负的大电阻温度系数（TCR）为-0.32%/K，这使得与未处理Ti热敏电阻的器件相比，响应率提高了约4.5倍。然而，由于闪烁噪声增加，这并没有改善噪声等效功率（NEP）。通过透射电子显微镜（TEM）、透射电子衍射（TED）和能量色散X射线（EDX）进行的微观结构分析证实，在加热后，最初沉积的Ti相（纯度约85%）上形成了氧化钛（TiO）半导体相。退火过程中TiO的形成可以最小化我们之前在细金属丝中报道的窄宽度效应，从而提高响应率。
