Direct MXene deposition on large-area 2D semiconductor
surfaces
can provide design versatility for the fabrication of MXene-based
electronic devices (MXetronics). However, it is challenging to deposit
highly uniform wafer-scale hydrophilic MXene films (e.g., Ti3C2Tx) on hydrophobic 2D semiconductor
channel materials (e.g., MoS2). Here, we demonstrate a
modified drop-casting (MDC) process for the deposition of MXene on
MoS2without any pretreatment, which typically degrades
the quality of either MXene or MoS2. Different from the
traditional drop-casting method, which usually forms rough and thick
films at the micrometer scale, our MDC method can form an ultrathin
Ti3C2Txfilm (ca.
10 nm) based on a MXene-introduced MoS2surface polarization
phenomenon. In addition, our MDC process does not require any pretreatment,
unlike MXene spray-coating that usually requires a hydrophilic pretreatment
of the substrate surface before deposition. This process offers a
significant advantage for Ti3C2Txfilm deposition on UV-ozone- or O2-plasma-sensitive
surfaces. Using the MDC process, we fabricated wafer-scalen-type Ti3C2Tx–MoS2van der Waals heterojunction transistors,
achieving an average effective electron mobility of ∼40 cm2·V–1·s–1, on/off
current ratios exceeding 104, and subthreshold swings of
under 200 mV·dec–1. The proposed MDC process
can considerably enhance the applications of MXenes, especially the
design of MXene/semiconductor nanoelectronics.