The fabrication of Schottky photodiode by monolayer graphene direct-transfer-on-silicon

A two-step hot embossing process was used to transfer graphene and to fabricate Gr/Si Schottky photodiodes. As a direct graphene transfer technique through a hot embossing system, chemical vapor deposition Gr monolayer was transferred from copper foil to cyclic olefin copolymer foil without a poly(methylmethacrylate) sacrificial layer. Then, hot embossing was employed once again to bond graphene with the prepared Si substrate to form Schottky contact. Electrical and photoelectrical characterizations have been performed to evaluate the Schottky photodiode. The photocurrent increases linearly with light intensity under 633 nm illumination. With an appropriate bias voltage, the maximum responsivity reaches 0.73 A/W. Extracted from I-V characteristics by Cheung's function, the Schottky barrier height and ideality factor are 1.01 eV and 2.66, respectively. The experimental result shows the feasibility and effectiveness of this hot embossing fabrication process, which demonstrates the opportunity for large scale production and provides a new approach for graphene optoelectronics.