Abstract
Metal-semiconductor contacts play a pivotal role in controlling carrier transport in the fabrication of modem electronic devices.The exploration of van der Waals(vdW)metal contacts in semiconductor devices can potentially mitigate Fermi-level pinning at the metal-semiconductor interface,with partic-ular success in two-dimensional layered semiconductors,triggering unprecedented electrical and optical characteristics.In this work,for the first time,we report the direct integration of vdW metal contacts with bulk wide bandgap gallium nitride(GaN)by employing a dry transfer technique.High-angle annular dark-field scanning transmission electron microscopy explicitly illustrates the existence of a vdW gap between the metal electrode and GaN.Strikingly,compared with devices fabricated with electron beam-evaporated metal contacts,the vdW contact device exhibits a responsivity two orders of magni-tude higher with a significantly suppressed dark current in the nanoampere range.Furthermore,by lever-aging the high responsivity and persistent photoconductivity obtained from vdW contact devices,we demonstrate imaging,wireless optical communication,and neuromorphic computing functionality.The integration of vdW contacts with bulk semiconductors offers a promising architecture to overcome device fabrication challenges,forming nearly ideal metal-semiconductor contacts for future integrated electronics and optoelectronics.
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