Current conduction across multilayer and delaminated MXene Schottky interfaces on <i>n</i> -GaAs and their photoresponse

We report the current conduction across multilayer and delaminated Ti3C2Tx two-dimensional transition metal carbides (MXene)-based Schottky interfaces formed on n-type GaAs. Two types of Ti3C2Tx MXene/n-type GaAs metal–semiconductor (MS) interfaces were created by a simple drop-casting technique using a multilayer MXene coating and a thin film of delaminated MXene. The Schottky barrier heights of the MS interfaces were analyzed from room-temperature as well as temperature-dependent current–voltage (I–V) characteristics across the junction. The Schottky barrier height calculated from the I–V data shows lower values for the delaminated MXene-based Schottky junctions compared to the multilayer-based device. We attribute this difference primarily to reduced Fermi-level pinning at the delaminated Ti3C2Tx/n-GaAs interface and to the presence of a large amount of trapped water in the multilayer Ti3C2Tx structure. The applicability of the rectifying Schottky interfaces as photodiodes was demonstrated as a photodiode at a wavelength of 785 nm. The delaminated MXene-based photodiode shows superior performance with a responsivity of 284 mAW−1 compared to the multilayer MXene-based device.