▎ 摘　　要

In this paper, we propose photodetectors based on sandwiched graphene nanoribbons and investigate their optical and electrical characteristics. Here we combine three narrow armchair graphene (AGNRs) in a way that two AGNRs with the same width sandwich another AGNR with a different width and smaller length. Some of these structures produce sharp peaks in their absorption spectrum that increase selectivity in some frequencies. Some of the peaks shift to mid-infrared, and so are useful in various optical communication windows. These structures also increase the absorption coefficient at some wavelengths up to 90-fold. The responsivity peak shows a maximum of about a 52% increase. We also show that some of these structures can reduce dark current by about three times. Finally, we demonstrate the effect of channel length on dark current in these devices. (C) 2016 Optical Society of America