High Performance β-Ga2O3 Schottky Barrier Transistors with Large Work Function TMD Gate of NbS2 and TaS2

Gallium trioxide, beta-Ga2O3, has been recently studied due to its promising semiconducting properties as active material in transistors or Schottky diodes. Transistors with beta-Ga2O3 channels are mostly metal oxide field effect transistors (MOSFET), and they show very negative threshold voltages (V-th) in general. Metal semiconductor field effect transistors (MESFETs) with top gate are also reported with less negative V-th. Still, beta-Ga2O3 MESFETs are only a few. Here, bottom gate architecture beta-Ga2O3 MESFETs using transition metal dichalcogenide (TMD) NbS2 and TaS2 are reported. Due to the large work functions of those metallic TMDs, the MESFETs display minimum subthreshold swing of 61 mV dec(-1), small V-th of -1.2 V, minimum OFF I-D of approximate to 100 fA, and maximum ON/OFF current ratio of approximate to 10(8). Both beta-Ga2O3 Schottky diodes with TaS2 and NbS2 display good junction stability even after 300 degrees C measurements in 10 mTorr vacuum. When the beta-Ga2O3 MESFET with TaS2 gate is integrated as a switching FET into an organic light emitting diode (OLED) circuit, it demonstrates long-term leakage endurance performance, maintaining an OLED brightness higher than 58% of the initial intensity after 100 s passes since the ON-switching point, which is even superior to the performance of conventional a-IGZO MOSFET switch.

Automated summary

The study presents bottom gate architecture beta-Ga2O3 MESFETs using transition metal dichalcogenide (TMD) NbS2 and TaS2. Due to the large work functions of these TMDs, the MESFETs demonstrate good performance, including minimum subthreshold swing and small threshold voltage.