Direct Growth of Graphene Nanowalls on Silicon Using Plasma-Enhanced Atomic Layer Deposition for High-Performance Si-Based Infrared Photodetectors

Development of materials and structures for cost-effective and room-temperature-operated infrared photodetectors (PDs) is highly required for security, telecommunications, and environmental sensing fields. Here, we report a method to directly grow large-area graphene nanowalls (GNWs) on the Si substrate by using the plasma-enhanced atomic layer deposition (PEALD) technique and high-performance GNWs-Si heterostructure infrared PDs based on the GNWs. We develop a PEALD protocol by using benzene as the carbon source and formic acid that provides oxygen to assist GNW growth on the Si substrate. Our PEALD-grown GNWs exhibits much better light absorption and in-plane electrical properties as compared to the GNW grown by conventional methods on the Si substrate. Our simple GNW-Si Schottky junction-based self-powered infrared PD exhibits a high responsivity of 15 mA/W at 1342 nm, a fast response speed of 43 μs for rise time and 69 μs for decay time, and a high specific detectivity of 1.5 × 10¹¹ cm Hz^1/2/W under a test condition of 10,000 Hz. Our study opens a promising venue to directly grow graphene materials on Si for Si-based optoelectronics.