Highly Sensitive Thermal Sensor Design Using a Gate-Bias-Controlled TCR in MoSe₂ FET

Temperature coefficient of resistance (TCR) is an important property for the design of thermal sensors. It is calculated as per the relative shift in electrical resistance for every degree of thermal variation. Furthermore, tunable TCR implies controlling the TCR through the manipulation of gate voltage. In this article, we have investigated the TCR tunability of the layered semiconductor material molybdenum diselenide (MoSe<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub>) with gate-bias control. Atomic force microscope (AFM) is used to measure flake height, and Raman spectroscopy is used to characterize the MoSe<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub> flakes. Their TCR is higher by about two times that of MoS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub> and five times that of metallic films, which are typically around 0.5% K<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-<roman>1</roman></sup>. Its TCR can be tuned to about two times higher than its value for 15-nm-thick flake within a gate voltage change of 7 V, with the highest recorded value being -2.75% K<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-<roman>1</roman></sup>. Similarly, 65-nm-thick flake has a TCR tunability of 4.5 times higher than the minimum value. Additionally, the average relative uncertainty in TCR is observed to be 3.8% for the 65-nm devices and 4.6% for the 15-nm devices, respectively.