Edge Effect on the Photodetection Ability of the Graphene Nanocrystallites Embedded Carbon Film Coated on p‐Silicon

A sensitive photodetector of graphene nanocrystallites embedded carbon (GNEC) film coated on p‐silicon has been proposed. Different from the conventional growth mode of graphene, GNEC film contains a large amount of vertically grown graphene nanocrystallites (GNs). Edges of GNs act as electron trapping centers, increasing the ability to capture electrons. Different types of films are prepared under various deposition biases (20, 40, 60, and 80 V), which have different density of edges (N_edge). Edge entrapment improves the photocurrent responsivity of 40 V film (high N_edge) to 0.401 A W⁻¹, compared with 0.126 A W⁻¹ of 20 V film (amorphous, no N_edge) and 0.194 A W⁻¹ of 80 V film (low N_edge). A high specific detectivity of 1.34 × 10¹² cm Hz^1/2 W⁻¹ is exhibited at zero bias. GNs maintain a charge transport channel, which makes it have a fast response time τ_rise = 260 ns.