CVD Graphene on Textured Silicon: An Emerging Technologically Versatile Heterostructure for Energy and Detection Applications

Abstract

Integration of chemical vapor deposited (CVD) graphene with textured‐Si substrates is an emerging research area wide open. Graphene can serve as both a transparent top electrode and a charge‐separating/transport‐active layer. However, its low light absorption capability, and high reflectance of planar‐Si substrate are major concerns for light harvesting required for photovoltaic devices especially solar cells and photodetectors (PDs). Therefore, CVD‐graphene/textured‐Si heterostructure effectively addresses this problem as the textured‐Si provides more surface area for light harvesting by suppressing light reflection and enables the efficient charge separation/transport as well. Recently, CVD‐graphene/textured‐Si Schottky junction based high performance solar cells and PDs have successfully been demonstrated. Moreover, the graphene coating on textured‐Si enhances the conductivity of Si anodes and provides structural stability for lithium‐ion batteries (LIBs). Furthermore, the optoelectronic coupled interfacial properties in such heterostructures suitably construct the platforms for surface enhanced Raman scattering (SERS) based detection and photocathodes for H2‐production, respectively. Hence, in this review, the fabrication of various CVD‐graphene/textured‐Si heterostructures and their applications in solar cells, PDs, SERS, LIBs, and H2‐production are critically analyzed with respect to the synergistic effect of Si‐texturing, electronic/optoelectronic properties of CVD‐graphene, etc. Finally, conclusions and outlook of this rapidly emerging and technologically broad research area are presented.

Chemical Vapor Deposition of Graphene on Self-Limited SiC Interfacial Layers Formed on Silicon Substrates for Heterojunction Devices

“…This was consistent with its XRD pattern and the corresponding Raman spectrum which exhibited the strong TO phonon mode attributed to 3C-SiC. It is also noteworthy that the peak corresponding to C−H sp 3 carbon which originates from the H-terminated graphene edges is missing in all spectra, which means that graphene growth did not occur on the self-limited SiC layers given that CH 4 corresponded to amorphous carbon which might have accumulated on top of the sample's surface after the formation of self-limited SiC layer. Since XPS is a surface-sensitive technique and all the spectra were acquired without altering the top surface, the prominent C�C sp 2 peaks belonging to amorphous carbon were observed for all the samples.…”

“…Consequently, this might have an impact on the functionality of graphene/Si heterostructure-based electronic and optoelectronic systems. Various low-temperature plasma-enhanced CVD (PECVD) techniques could be used to directly generate graphene on Si substrates in order to alleviate this problem. ,,− Generally, by using such PECVD techniques, vertical graphene structures or graphene nanowalls (GNWs) are obtained on Si rather than high-quality horizontal graphene films. Several optoelectronic devices based on GNW/Si heterostructures have already been demonstrated such as solar cells, , photodetectors, ,,,, and so forth.…”

“…For the purpose of creating Schottky junction-based electronic and optoelectronic technologies, the synthesis of graphene/Si heterostructures is receiving a lot of interest. − The ideal method for creating such heterostructures is to develop graphene using direct chemical vapor deposition (CVD) growth on Si substrates without the use of a metal catalyst. , However, utilizing a thermal CVD technique to generate graphene directly on Si substrates at temperatures ≥800 °C is a challenging task because it results either in the production of only a very small-sized scattered graphitic structures or no graphene formation at all. − This is due to the high solubility and extremely poor diffusivity of carbon atoms on Si substrates, which prevent the development of graphene. − The rapid creation of a thin SiC layer, which occurs before the graphene growth, in fact, is unavoidable during the direct thermal CVD production of graphene on Si at ≥900 °C. , And if graphene development does occur, it must do so on the thin SiC layer that has already developed . Consequently, this might have an impact on the functionality of graphene/Si heterostructure-based electronic and optoelectronic systems.…”

Graphene/Graphene Derivatives from Coal, Biomass, and Wastes: Synthesis, Energy Applications, and Perspectives

“…In addition to their utilization as electrode materials in energy storage devices, graphene is also applicable for energy conversion as well as energy generation purposes. ,,, In devices like fuel cells (FCs) and dye-sensitized solar cells (DSSCs), graphene plays an important role in the efficient conversion of chemical/solar energies into electrical energy. In FCs, graphene derivatives were suitably applied for decreasing the loading of Pt-based catalysts, as a catalyst support/standalone catalyst, or as an electrolyte membrane with the similar performances to that of other materials. − In the case of dye-synthesized solar cells, graphene derivatives were found to be improving the efficiency as well as stability of DSSCs by employment at the photoanode, electrolyte, and the counter electrode. − As these energy converting/harvesting devices utilize the expensive and limited Pt-based catalysts, the use of graphene derivatives as an alternative as well as supportive material not only reduces the cost but also acts as a viable replacement with accepted performance and stability.…”

Graphene/Si Heterostructure with an Organic Interfacial Layer for a Self-Powered Photodetector with a High ON/OFF Ratio

“…Photodetectors (PDs) are widely used in various fields of military and daily life especially for imaging, telecommunications, sensing, and so on. Therefore, high performance and low power consumption are of crucial importance for PDs with high detectivity and fast response speed. − A self-powered PD that can work at 0 V bias helps to achieve high detectivity and low power consumption. , In the meantime, graphene materials with unique optical and electronic properties have attracted a lot of attention. , Si and graphene in direct contact can form a reliable Schottky junction, and therefore, photogenerated carriers can be effectively separated at the junction without applied voltage. − Moreover, several graphene/Si heterostructure-based PDs have successfully been demonstrated. − However, the interface trap states coupled with a low Schottky junction barrier reduce response speed and increase noise current, which eventually hinder their high-performance applications. − …”