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 (lambda = 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 approximate to 5 x 10(5) 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.