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

Abstract

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 ∼2.66 × 10¹² cm H^1/2 W⁻¹ and excellent sensitivity of ∼1.8 × 10⁶ cm² 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 × 10⁵ cm² W⁻¹ and detectivity of ∼2.5 × 10¹¹ 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.