Ultrahigh broadband photoresponse of SnO2 nanoparticle thin film/SiO2/p-Si heterojunction

摘要

The SnO2/Si heterojunction possesses a large band offset and it is easy to control the transportation of carriers in the SnO2/Si heterojunction to realize high-response broadband detection. Therefore, we investigated the potential of the SnO2 nanoparticle thin film/SiO2/p-Si heterojunction for photodetectors. It is demonstrated that this heterojunction shows a stable, repeatable and broadband photoresponse from 365 nm to 980 nm. Meanwhile, the responsivity of the device approaches a high value in the range of 0.285-0.355 A W-1 with the outstanding detectivity of similar to 2.66 x 10(12) cm H-1/2 W-1 and excellent sensitivity of similar to 1.8 x 10(6) cm(2) W-1, and its response and recovery times are extremely short (<0.1 s). This performance makes the device stand out among previously reported oxide or oxide/Si based photodetectors. In fact, the photosensitivity and detectivity of this heterojunction are an order of magnitude higher than that of 2D material based heterojunctions such as (Bi2Te3)/Si and MoS2/graphene (photosensitivity of 7.5 x 10(5) cm(2) W-1 and detectivity of similar to 2.5 x 10(11) cm H-1/2 W-1). The excellent device performance is attributed to the large Fermi energy difference between the SnO2 nanoparticle thin film and Si, SnO2 nanostructure, oxygen vacancy defects and thin SiO2 layer. Consequently, practical highly-responsive broadband PDs may be actualized in the future.