2D-3D integration of hexagonal boron nitride and a high-κ dielectric for ultrafast graphene-based electro-absorption modulators

• DOI: 10.1038/s41467-021-20926-w
• Publication Date: 2021-02-17T18:37:58Z
• Authors: Hitesh Agarwal; Bernat Terrés; Lorenzo Orsini; Alberto Montanaro; Vito Sorianello; Marianna Pantouvaki; Kenji Watanabe; Takashi Taniguchi; Dries Van Thourhout; Marco Romagnoli; Frank H. L. Koppens
• Keywords: Technology and Engineering; Science; Q; OPERATION; BREAKDOWN; 02 engineering and technology; ELECTROOPTIC MODULATOR; OPTICAL MODULATORS; SILICON; 0210 nano-technology; Article

AbstractElectro-absorption (EA) waveguide-coupled modulators are essential building blocks for on-chip optical communications. Compared to state-of-the-art silicon (Si) devices, graphene-based EA modulators promise smaller footprints, larger temperature stability, cost-effective integration and high speeds. However, combining high speed and large modulation efficiencies in a single graphene-based device has remained elusive so far. In this work, we overcome this fundamental trade-off by demonstrating the 2D-3D dielectric integration in a high-quality encapsulated graphene device. We integrated hafnium oxide (HfO2) and two-dimensional hexagonal boron nitride (hBN) within the insulating section of a double-layer (DL) graphene EA modulator. This combination of materials allows for a high-quality modulator device with high performances: a ~39 GHz bandwidth (BW) with a three-fold increase in modulation efficiency compared to previously reported high-speed modulators. This 2D-3D dielectric integration paves the way to a plethora of electronic and opto-electronic devices with enhanced performance and stability, while expanding the freedom for new device designs.