A thin film approach for SiC-derived graphene as an on-chip electrode for supercapacitors

High quality epitaxial graphene on 4H-SiC by face-to-face growth in ultra-high vacuum

Epitaxial graphene on SiC is the most promising substrate for the next generation 2D electronics, due to the possibility to fabricate 2D heterostructures directly on it, opening the door to the use of all technological processes developed for silicon electronics. To obtain a suitable material for large scale applications, it is essential to achieve perfect control of size, quality, growth rate and thickness. Here we show that this control on epitaxial graphene can be achieved by exploiting the face-to-face annealing of SiC in ultra-high vacuum. With this method, Si atoms trapped in the narrow space between two SiC wafers at high temperatures contribute to the reduction of the Si sublimation rate, allowing to achieve smooth and virtually defect free single graphene layers. We analyse the products obtained on both on-axis and off-axis 4H-SiC substrates in a wide range of temperatures (1300 °C-1500 °C), determining the growth law with the help of x-ray photoelectron spectroscopy (XPS). Our epitaxial graphene on SiC has terrace widths up to 10μm (on-axis) and 500 nm (off-axis) as demonstrated by atomic force microscopy and scanning tunnelling microscopy, while XPS and Raman spectroscopy confirm high purity and crystalline quality.

Graphene Film Growth on Silicon Carbide by Hot Filament Chemical Vapor Deposition

The electrical properties of graphene on dielectric substrates, such as silicon carbide (SiC), have received much attention due to their interesting applications. This work presents a method to grow graphene on a 6H-SiC substrate at a pressure of 35 Torr by using the hot filament chemical vapor deposition (HFCVD) technique. The graphene deposition was conducted in an atmosphere of methane and hydrogen at a temperature of 950 °C. The graphene films were analyzed using Raman spectroscopy, scanning electron microscopy, atomic force microscopy, energy dispersive X-ray, and X-ray photoelectron spectroscopy. Raman mapping and AFM measurements indicated that few-layer and multilayer graphene were deposited from the external carbon source depending on the growth parameter conditions. The compositional analysis confirmed the presence of graphene deposition on SiC substrates and the absence of any metal involved in the growth process.

Advances in Si and SiC Materials for High-Performance Supercapacitors toward Integrated Energy Storage Systems

Silicon (Si), as the second most abundant element on Earth, has been a central platform of modern electronics owing to its low mass density and unique semiconductor properties. From an energy perspective, all-in-one integration of power supply systems onto Si-based functional devices is highly desirable, which inspires significant study on Si-based energy storage. Compared to the well-known Si-anode Li-ion batteries, Si-based supercapacitors possess high power density, long life, and simple working mechanisms, which enables their ease of integration onto a wide range of devices and applications. Besides Si, silicon carbide (SiC), as a physicochemically stable wide-bandgap semiconductor, also attracts research attention as an energy storage material in harsh environments. In this review, a detailed overview of latest advances in materials design, synthesis methods, and performances of Si-based and SiC-based supercapacitors will be provided. Some successful integrated devices, future perspectives, and potential research directions are also highlighted and discussed.