Nanogap Patterning Technique for Electrostatic Doping-based Reconfigurable Homogeneous PN Junction Diode

초록

Layered two-dimensional van der Waals (2D vdWs) materials have been studied for their dangling bonds-free property and excellent electrical performances. Since the emergence of graphene, the field of 2D electronics based on vdWs materials is now expanding beyond gap-less conducting graphene into transition metal dichalcogenides (TMDCs) semiconductors and hexagonal boron nitride (h-BN) insulator as well. Among various TMDCs, the PdSe2 has strong ambipolar semiconducting property which shows both n-type and p-type transitions [1]. This distinct ambipolar transport is identified in a transfer characteristic (V￢G-ID curves) of metal-insulator-semiconductor field-effect transistor (MISFET), implying either hole or electron doping can be achieved by VG. In this work, the reconfigurable PdSe2 homojunction pn diode based on electrostatic doping effect was investigated by controlling VG at nano-gapped gate electrodes [2, 3]. In order to achieve a pair of separated gate electrodes, we demonstrated a simple nano-pattering technique based on conventional photo-lithography and lift-off processes by using ZnO nanowires as a shadow mask. Our proposed technique can define the nano-gapped electrodes according to the diameter of ZnO nanowire. The PdSe2 homojunction pn diode, flipable rectifying direction, showed an ideality factor of ~1.99 and ON/OFF current ratio of ~102. In order to explore our study, the single-inversion AND (SAND) logic gate was implemented [4]. This universal SAND logic gate can be expected to be applicable to detect phase leading or lagging signal.