Low-Temperature Synthesis of Boron Nitride as a Large-Scale Passivation and Protection Layer for Two-Dimensional Materials and High-Performance Devices

Abstract

Two-dimensional materials (2DMs) with extraordinary electronic and optical properties have attracted great interest in optoelectronic applications. Due to their atomically thin feature, 2DM-based devices are generally sensitive to oxygen and moisture in ambient air, and thus, practical application of durable 2DMbased devices remains challenging. Here, we report a novel strategy to directly synthesize amorphous BN film on various 2DMs and field-effect transistor (FET) devices at low temperatures by conventional chemical vapor deposition. The wafer-scale BN film with controllable thickness serves as a passivation and heat dissipation layer, further improving the long-term stability, the resistance to laser irradiation, and the antioxidation performance of the underneath 2DMs. In particular, the BN capping layer could be deposited directly on a WSe 2 FET at low temperature to achieve a clean and conformal interface. The high performance of the BNcapped WSe 2 device is realized with suppressed current fluctuations and 10-fold enhanced carrier mobility. The transfer-free amorphous BN synthesis technique is simple and applicable to various 2DMs grown on arbitrary substrates, which shows great potential for applications in future two-dimensional electronics.

Low-Temperature Direct Growth of Amorphous Boron Nitride Films for High-Performance Nanoelectronic Device Applications

“…As an alternative for the crystalized h-BN, amorphous boron nitride (a-BN) has been considered a promising encapsulating material for 2DMs because it is relatively free of defects (traps and dangling bonds) and requires low growth temperature. 26 − 31 Glavin et al and Hong et al explored the dielectric properties of ultrathin a-BN film and diffusion barrier behavior for ultrathin electronic devices. 28 , 29 Uddin et al confirmed that FETs of graphene on an a-BN heterointerface could enhance the hole and electron mobilities to 4980 and 4200 cm 2 /Vs, respectively.…”

“… 30 Very recently, Lu et al verified that a-BN film successfully suppresses current fluctuations and enhances carrier mobility of 2D materials. 31 However, fabricating a-BN films still has several issues, such as the requirement of additional annealing processes at relatively high temperatures, complicated processes for making the protection layer, and the debate over the transfer process. Above all, experiments to confirm whether a-BN can sufficiently protect 2D materials from the external environment and help improve electrical performance have not been appropriately explored or performed yet ( Table S2 ).…”

“…In addition, to obtain an h-BN film with a large area, a high growth temperature and a long growth time are required. As an alternative for the crystalized h-BN, amorphous boron nitride (a-BN) has been considered a promising encapsulating material for 2DMs because it is relatively free of defects (traps and dangling bonds) and requires low growth temperature. − Glavin et al and Hong et al explored the dielectric properties of ultrathin a-BN film and diffusion barrier behavior for ultrathin electronic devices. , Uddin et al confirmed that FETs of graphene on an a-BN heterointerface could enhance the hole and electron mobilities to 4980 and 4200 cm 2 /Vs, respectively . Very recently, Lu et al verified that a-BN film successfully suppresses current fluctuations and enhances carrier mobility of 2D materials .…”

“…As an alternative for the crystalized h-BN, amorphous boron nitride (a-BN) has been considered a promising encapsulating material for 2DMs because it is relatively free of defects (traps and dangling bonds) and requires low growth temperature. − Glavin et al and Hong et al explored the dielectric properties of ultrathin a-BN film and diffusion barrier behavior for ultrathin electronic devices. , Uddin et al confirmed that FETs of graphene on an a-BN heterointerface could enhance the hole and electron mobilities to 4980 and 4200 cm 2 /Vs, respectively . Very recently, Lu et al verified that a-BN film successfully suppresses current fluctuations and enhances carrier mobility of 2D materials . However, fabricating a-BN films still has several issues, such as the requirement of additional annealing processes at relatively high temperatures, complicated processes for making the protection layer, and the debate over the transfer process.…”