High responsivity in MoS2 phototransistors based on charge trapping HfO2 dielectrics

Abstract

Abstract2D Transition Metal Dichalcogenides hold a promising potential in future optoelectronic applications due to their high photoresponsivity and tunable band structure for broadband photodetection. In imaging applications, the detection of weak light signals is crucial for creating a better contrast between bright and dark pixels in order to achieve high resolution images. The photogating effect has been previously shown to offer high light sensitivities; however, the key features required to create this as a dominating photoresponse has yet to be discussed. Here, we report high responsivity and high photogain MoS2 phototransistors based on the dual function of HfO2 as a dielectric and charge trapping layer to enhance the photogating effect. As a result, these devices offered a very large responsivity of 1.1 × 106 A W−1, a photogain >109, and a detectivity of 5.6 × 1013 Jones under low light illumination. This work offers a CMOS compatible process and technique to develop highly photosensitive phototransistors for future low-powered imaging applications.

Chemical vapor deposition merges MoS2 grains into high-quality and centimeter-scale films on Si/SiO2

“…5(e)) and reaches values in excess of $420 A W À1 in two-terminal co-planar geometry. This value represents the quite higher responsivity of MoS 2 as compared to other reports 11,41,52,53 (for a comparison to literature, see the ESI S3 †) and indicates the benets of producing MoS 2 with low trap density and efficient carrier conduction. More importantly, uniformly high responsivity could be achieved for all devices throughout the centimetre-sized samples (Fig.…”

A floating gate negative capacitance MoS2 phototransistor with high photosensitivity

“…The photogating effect relies on the trapping of the photogenerated holes at the dielectric/semiconductor interface, which results in developing a local built-in electric field that shifts the Fermi level to induce more electrons. 19,20,42 In addition, to evaluate the enhancement in photodetection with the NCFG device structure, a conventional back-gate TiN-ZrO 2 and Si-ZrO 2 device were measured and their photoresponse results can be found in Fig. 3b and c respectively.…”

“…The maximum change in the threshold voltage shifting was −0.92 V for 51.8 μW cm −2 which is quite a low light intensity in comparison with other MoS 2 phototransistors that have been investigated for photogating at higher optical powers. 7,20–22…”

The Low-Temperature Photocurrent Spectrum of Monolayer MoSe2: Excitonic Features and Gate Voltage Dependence

“…In TMD-based phototransistors, photocurrent typically emerges from two different mechanisms: the photoconductive effect (PCE), where light-induced formation of electron–hole pairs leads to increased charge carrier density and electrical conductivity; and the photogating effect (PGE), where the light-induced filling or depletion of localized states causes a shift in the Fermi energy [ 19 , 20 ]. These two mechanisms can be distinguished by their different dependence on the gate voltage—while PCE-generated photocurrent typically depends weakly on V g , PGE produces a gate-voltage-dependent photocurrent proportional to the out-of-plane transconductance [ 21 , 22 , 23 ].…”