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

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 (Eg ≈ 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. Highly crystalline 2D/3D‐mixed p‐TMD/n‐Ga2O3 heterojunction devices are fabricated by mechanical exfoliation of each p‐ and n‐type material, to finally realize ambipolar channel junction field‐effect transistors (JFETs) as well as PN diodes. For more extended applications, p‐TMD channel JFETs are used to sense visible or NIR photons through the β‐Ga2O3 at high speed.