Ambipolar Channel p-TMD/n-Ga2 O3 Junction Field Effect Transistors and High Speed Photo-sensing in TMD Channel.

Abstract

Highly crystalline 2D/3D-mixed p-transition metal dichalcogenide (TMD)/n-Ga2 O3 heterojunction devices are fabricated by mechanical exfoliation of each p- and n-type material. N-type β-Ga2 O3 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-Ga2 O3 (Eg ≈ 4.8eV) is taken advantage of, firstly to measure the electrical energy gap of p-TMDs receiving visible or near infrared (NIR) photons through the β-Ga2 O3 . Next, the p-TMD/n-Ga2 O3 JFETs are put to high speed photo-sensing which is achieved from the p-TMD channel under reverse bias voltages on n-Ga2 O3 . The photo-switching cutoff frequency appears to be ≈16 and 29kHz for visible red and NIR illuminations, respectively, on the basis of -3dB 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.