Substrate effects in high gain, low operating voltage SnSe₂photoconductor

Abstract

High gain photoconductive devices find wide spread applications in low intensity light detection. Ultra-thin layered materials have recently drawn a lot of attention from researchers in this regard. However, in general, a large operating voltage is required to obtain large responsivity in these devices. In addition, the characteristics are often confounded by substrate induced trap effects. Here we report multi-layer SnSe based photoconductive devices using two different structures: (1) SiO substrate supported inter-digitated electrode (IDE), and (2) suspended channel. The IDE device exhibits a responsivity of [Formula: see text] A W and [Formula: see text] A W at operating voltages of 1 mV and 100 mV, respectively-a superior low voltage performance over existing literature on planar 2D structures. However, the responsivity reduces by more than two orders of magnitude, while the transient response improves for the suspended device-providing insights into the critical role played by the channel-substrate interface in the gain mechanism. The results, on one hand, are promising for highly sensitive photoconductive applications consuming ultra-low power, and on the other hand, show a generic methodology that could be applied to other layered material based photoconductive devices as well for extracting the intrinsic behavior.

Strong Single- and Two-Photon Luminescence Enhancement by Nonradiative Energy Transfer across Layered Heterostructure

“…This is in agreement with our previous KPFM measurements which show that the SnSe2 is degenerately n-doped with the Fermi level about 0.3 eV above conduction band (CB) minimum. 40 The screening offered by the large carrier concentration suppresses strongly bound exciton state in SnSe2. Throughout this paper, we thus assume that the transition dipole in SnSe2 is governed by free electron-hole pairs.…”

2D library beyond graphene and transition metal dichalcogenides: a focus on photodetection

“…183 Raman spectroscopy has been shown to be a feasible tool to define the thickness of SnSe 2 , in which the difference between the two Raman peaks, namely E g and A 1g (located at B110 and B188 cm À1 , respectively), increases as the thickness decreases. 184 The photoresponse range of SnSe 2 can extend to the IR range. Using thick films, Mukhokosi et al demonstrated SnSe 2 photodetectors with R as high as B2 mA W À1 to 1064 nm light.…”

Accurate Extraction of Schottky Barrier Height and Universality of Fermi Level De-pinning of van der Waals Contacts

“…To further validate this method, we fabricated a separate TaSe 2 -WS 2 -SnSe 2 stack where SnSe 2 is a degenerately n-doped, highly conductive layered semiconductor. 21 The extracted SBH value of SnSe 2 is 0.71 eV (See Supporting Figure S4), which corresponds to S = 0.8, indicating a highly de-pinned contact.…”