An Ultrahigh-Rectification-Ratio WSe₂ Homojunction Defined by High-Efficiency Charge Trapping Effect

Although 2D material van der Waals heterostructures (vdWHs) exhibit many novel properties and applications, 2D homojunctions have unique advantages in interface lattice matching, band continuity, and charge transfer efficiency. However, the rectification performances of 2D homojunction diodes are severely limited by the small junction barrier, mainly due to inefficient charge doping. In this work, an ultrahigh-rectification-ratio WSe2 homojunction diode achieved by the semi-floating gate doping of graphdiyne oxide (GDYO) is reported. Utilizing the WSe2/GDYO direct charge trapping mode can free the inhibition of charge capturing efficiency by removing conventional insulating barriers and thus improve the rectification ratio. The C & horbar;C(sp) and oxygen-containing functional groups in the GDYO layer can provide outstanding charge-trapping ability due to their unsaturation. Furthermore, the oxygen plasma treatment used for oxidizing graphdiyne (GDY) into GDYO can make GDYO a flatter surface, thus creating strong-coupling WSe2/GDYO interfaces to improve the charge transfer efficiency and enhance the electrostatic doping effect. Besides, the WSe2/GDYO interfaces are confirmed to possess a higher junction barrier than that of the WSe2/GDY interfaces. This research proposes a brand-new approach to building p-n junctions via charge trapping and the homojunction diode with a record-highest rectification ratio of up to 10(6) is obtained.