Transfer-free fabrication of graphene transistors

TL;DR

This paper introduces a novel transfer-free method for fabricating graphene transistors directly on oxidized silicon wafers using a nanometer-thin aluminum/nickel catalyst and CCVD growth, enabling low-cost integration in silicon electronics.

Contribution

The authors developed a transfer-free, silicon-compatible process for directly growing graphene transistors on oxidized silicon wafers, eliminating the need for graphene transfer steps.

Findings

Successful growth of monolayer and multilayer graphene directly on silicon wafers.

Raman spectroscopy confirms the presence and quality of graphene layers.

The process enables low-cost, scalable fabrication of graphene transistors.

Abstract

We invented a method to fabricate graphene transistors on oxidized silicon wafers without the need to transfer graphene layers. To stimulate the growth of graphene layers on oxidized silicon a catalyst system of nanometer thin aluminum/nickel double layer is used. This catalyst system is structured via liftoff before the wafer enters the catalytic chemical vapor deposition (CCVD) chamber. In the subsequent methane based growth process monolayer graphene field-effect transistors (MoLGFETs) and bilayer graphene transistors (BiLGFETs) are realized directly on oxidized silicon substrate, whereby the number of stacked graphene layers is determined by the selected CCVD process parameters, e.g. temperature and gas mixture. Subsequently, Raman spectroscopy is performed within the channel region in between the catalytic areas and the Raman spectra of fivelayer, bilayer and monolayer graphene confirm the existence of graphene grown by this silicon-compatible, transfer-free and in-situ fabrication approach. These graphene FETs will allow a simple and low-cost integration of graphene devices for nanoelectronic applications in a hybrid silicon CMOS environment.