Understanding the transport and contact properties of metal/BN-MoS₂ interfaces to realize high performance MoS₂ FETs

Understanding the nature of contact with BN buffer layer is vital to realize high performance monolayer MoS₂ nanodevice. Here, effects of BN buffer layer with different sizes and defects on the transport and contact properties of metal/BN-MoS₂ interfaces in six typical field effect transistors are comprehensively studied. No matter what the sizes or defects for BN buffer layer, the room-temperature electron mobilities (93.15 cm²V⁻¹s⁻¹) of MoS₂ channel layer and Fermi level pinning (∼0.43) of metal/BN-MoS₂ interfaces are not deteriorated, and all Schottky barriers at the metal/BN regions of metal/BN-MoS₂ interfaces are vanished. Interestingly, Schottky barriers the BN-MoS₂ regions of metal/BN-MoS₂ interfaces are irrelevant to the size of BN buffer layer, but reduced and enhanced by electron-poor and rich defects, respectively; while Schottky barriers between metal/BN-MoS₂ interfaces and MoS₂ channel layers are enhanced by all defects, and related to the sizes of defective BN buffer layers. Consequently, just when metal/BN-MoS₂ interfaces possess large size BN buffer layer, and meanwhile electron-poor defects locate at the channel region, the effective Schottky barriers are further reduced. In addition, tunnel barriers of metal/BN-MoS₂ interfaces are irrelevant to the sizes of BN buffer layers, but are reduced by electron-rich defects. These works systematically elucidate the contact and transport properties of metal/BN-MoS₂ interfaces and provide a promising way to design high performance monolayer FETs with lower Schottky barriers by defective BN buffer layer.