Direct integration of polycrystalline graphene on silicon as a photodetector via plasma-assisted chemical vapor deposition

Graphene that is directly integratable into electronic devices after its growth is highly desirable but is difficult to fabricate due to its relatively high growth temperatures (∼1000 °C) and inevitable transfer step. Herein, we propose a convenient and feasible strategy to directly synthesize high-quality polycrystalline graphene on Si substrates by utilizing plasma-assisted chemical vapor deposition (PACVD), where three main features inevitable to traditional growth methods, i.e., transition metals as catalysts, post-transfer process and high growth temperature, can be thoroughly circumvented. Notably, the growth temperature is significantly reduced and reaches as low as 700 °C. The utilized PACVD provides exceptional abilities of hydrocarbon pyrolysis and graphene formation even on unusual Si substrates. Furthermore, the as-grown graphene-on-Si (GOS) exhibits superior capabilities that can be used to directly fabricate high performance optoelectronic devices, e.g., photodetectors. Typical current rectification characteristics and good photovoltaic conversion efficiency are demonstrated in as-grown graphene/Si Schottky junctions.