Tungsten Dichalcogenide Nanoflake/InGaZnO Thin‐Film Heterojunction for Photodetector, Inverter, and AC Rectifier Circuits.

Heterojunction PN diode and inverter circuits are fabricated and presented, combining two‐dimensional WSe2 nanoflake and amorphous InGaZnO (a‐IGZO) thin film on a glass substrate. A heterojunction p‐WSe2/n‐IGZO diode exhibits rectifying characteristics and effectively responds to red light (λ = 620 nm) under a reverse bias. The combination of a heterojunction PN diode and IGZO field effect transistor (FET) leads to a diode‐load inverter showing a peak voltage gain of about 12 at a supply voltage of 5 V. The same integration from the PN diode and n‐FET displays the capability of visible light detection when a reverse‐bias voltage is applied to the PN diode. Furthermore, after oxygen plasma treatment on the PN diode, it shows dramatically enhanced on/off rectification ratio of ≈5 × 105 due to the hole doping effect on the WSe2 nanoflake. Such an improved PN diode leads to an alternating current rectifier circuit as integrated with IGZO FET. [ABSTRACT FROM AUTHOR]