Measurement of the temperature coefficient of resistance (TCR) of two-dimensional materials encapsulated with hBN for sensing layer of microbolometer

Abstract

The microbolometer, a type of thermal infrared sensor, detects the temperature change of its sensing layer caused by incident infrared as a change in resistance. This change in resistance is then represented as an electrical signal. Consequently, the sensor's performance is determined by the characteristics of the sensing layer, particularly the temperature coefficient of resistance(TCR) and heat capacity. However, commercial microbolometers face a significant challenge that they cannot simultaneously improve both noise equivalent temperature difference(NETD) and time constant, which are the key performance indicators. In this study, it is aimed to fabricate a sensor using a suspended 2-dimensional(2D) material as a sensing layer. Due to their layered structures, 2D materials are known to exhibit fewer defects and various properties. In addition, MoTe2 and MoS2, which are candidates for the sensing layer, can fulfill the requirements for a fast and sensitive sensing layer because, unlike metals, they maintain a high TCR even at atomically thin thicknesses. However, due to their high sensitivity to the surrounding environment, MoTe2 and MoS2 were encapsulated with hBN to stabilize them electrically. They were then transferred to the suspended structure for electrical measurement. The rate of resistance change was confirmed by measuring the resistance over time for the fabricated samples, and then the TCR near the room temperature is calculated.