Abstract
Van der Waals heterostructure shows promising applications in next generation optoelectronics. As a kind of van der Waals heterostructure, graphene/silicon (Gr/Si) based heterostructure devices have been demonstrated as high performance photodetectors. Here, we studied the origin of the high performance of Gr/Si photodetectors based on photocurrent mapping technology. According to photocurrent mapping, the photocurrent in the Gr/Si and Gr/SiO2/Si area nearing the Si window edge is higher than that in other positions, which is attributed to the highly effective collection efficiency of photocarriers. A device with size of Gr/Si region (r=7.4 μm) and Gr/SiO2/Si region (L=6.1 μm) shows high sensitivity and a broadband photoresponse in the range from 420 to 1000 nm with the peak sensitivity of 52 A/W at 780 nm, and fast response speed with rise time of 16 μs and decay time of 52 μs. Our study provides a strategy for the design of high photoresponsivity Gr/Si based devices.
Highlights
Layered two-dimensional (2D) materials have attracted tremendous attention in recent years due to their excellent physical and chemical properties
The device showed a higher responsivity of 635 mA/W compared with previous work, owing to the highly effective collection of charge carriers photogenerated in Si under the Gr/SiO2/Si parts
With the increase of L, the photocurrents increase obviously. It means that the Gr/SiO2/Si region shows remarkable photoresponse [9, 10, 12, 15]
Summary
Layered two-dimensional (2D) materials have attracted tremendous attention in recent years due to their excellent physical and chemical properties. The device showed a higher responsivity of 635 mA/W compared with previous work, owing to the highly effective collection of charge carriers photogenerated in Si under the Gr/SiO2/Si parts.
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