Photoresist-enabled assembly of BN/graphene/BN heterostructure and fabrication of one-dimensional contact electrode

Abstract

A poly(methyl methacrylate) (PMMA) substrate is easily soluble in acetone and cannot withstand high temperatures, thereby restricting the application of graphene or boron nitride (BN) on it. Furthermore, the assembly mechanism of a BN/graphene/BN heterostructure directly determines the performance of a device. In this paper, we report the single-spin photoresist stacking transfer assembly (SPSTA) of a BN/graphene/BN heterostructure on a PMMA substrate using a photoresist as a support layer. The photoresist served as a protective layer for the retained BN/graphene/BN heterostructure. The excess BN/graphene/BN heterostructure was etched away by oxygen plasma, following which a metal was evaporated on the photoresist surface. As metal is impervious to light, the excellent light transmittance of the PMMA substrate could be utilized. After the photoresist was denatured by ultraviolet light exposure on the back of the substrate, it was dissolved by a sodium hydroxide (NaOH) solution, and a one-dimensional contact of the BN/graphene/BN heterostructure and metal was achieved. Finally, through different testing methods, we found that the SPSTA of the BN/graphene/BN heterostructure yields a smooth morphology and high electrical conductivity with a uniform sheet resistance. We examined the air failure of the BN/graphene/BN heterostructure and found that its SPSTA was stable. Our study realized the transfer of two-dimensional (2D) materials on PMMA substrates for the first time, overcame the membrane surface pollution caused by the traditional BN/graphene/BN heterostructure assembly process, realized the fabrication of BN/graphene/BN heterostructure devices on PMMA substrates for the first time, and offers important insights for the application of graphene and BN or other 2D materials on PMMA substrates.