[10a-N305-1~10] CS.8 Code-sharing Session of 4.5 & 17

▲ [10a-N305-3] Monolayer MoS₂ Phototransistors using Ferroelectric Hf_0.5Zr_0.5O₂ Dielectrics

〇(DC)Roda Nur¹, Kasidit Toprasertpong¹, Shinichi Takagi¹, Mitsuru Takenaka¹ (1.The University of Tokyo)

Keywords:MoS2, ferroelectric, phototransistor

Atomically thin 2D materials such as MoS₂ exhibits interesting optoelectronic properties that have been utilized in applications such as photodetectors, light emitting diodes, and opto-valleytronic devices. Photodetectors are used in various applications such as image sensing, surveillance, and biomedical imaging. Research efforts in photodetectors have been focused towards exploring materials and device structures to improve the incident light absorption and light conversion efficiency. Steep slope transistor device structures that overcome the 60 mV/dec limitation due to the Boltzmann factor kT/q at room temperature holds a promising potential in photodetection applications. In particular, negative capacitance-based field effect transistors (NCFETs) are expected to overcome this constraint¹. This device structure has a possibility to offer low I_off currents allowing for lower dark current suppression resulting in an increase in the light detection sensitivity and enhancement in the detection of weak light signals. In this study, we explore monolayer MoS₂ phototransistors driven by a ferroelectric capacitor consisting of a TiN/Hf_0.5Zr_0.5O₂ (HZO)/TiN/ZrO₂ gate stack. A sub-60 mV/dec subthreshold swing was achieved and the dark current was measured in the range of ~10^-14A. Its photoresponse under green light illumination was characterized where it was found that its dominating photocurrent generation mechanism is the photogating effect². In addition, we evaluated its photodetection metrics as a potential promising sensitive low-powered photodetector.