Ambipolar Channel p‐TMD/n‐Ga₂O₃ Junction Field Effect Transistors and High Speed Photo‐sensing in TMD Channel

Abstract Highly crystalline 2D/3D‐mixed p‐transition metal dichalcogenide (TMD)/n‐Ga₂O₃ heterojunction devices are fabricated by mechanical exfoliation of each p‐ and n‐type material. N‐type β‐Ga₂O₃ and p‐type TMD separately play as a channel for junction field effect transistors (JFETs) with each type of carriers as well as materials for a heterojunction PN diode. The work thus mainly focuses on such ambipolar channel transistors with two different types of channel in a single device architecture. For more extended applications, the transparency of high energy band gap β‐Ga₂O₃ (E_g ≈ 4.8 eV) is taken advantage of, firstly to measure the electrical energy gap of p‐TMDs receiving visible or near infrared (NIR) photons through the β‐Ga₂O₃. Next, the p‐TMD/n‐Ga₂O₃ JFETs are put to high speed photo‐sensing which is achieved from the p‐TMD channel under reverse bias voltages on n‐Ga₂O₃. The photo‐switching cutoff frequency appears to be ≈16 and 29 kHz for visible red and NIR illuminations, respectively, on the basis of −3 dB photoelectric power loss. Such a high switching speed of the JFET is attributed to the fast transport of photo‐carriers in TMD channels. The 2D/3D‐mixed ambipolar channel JFETs and their photo‐sensing applications are regarded novel, promising, and practically easy to achieve.