High-Gain, Broadband Ultraviolet Photodetection with a Mixed-Dimensional van der Waals Heterostructure

Fig. 1 Device structure, measurement scheme, and optical characterization. (a) Schematic diagram of the ZrS2 QDs/MoS2 vdWH photodetector. (b) Optical images of the photodetector before (left) and after (right) the spin coating of the ZrS2 QDs. The channel length of the photodetector is 5 um, and the average channel width is 25 um. (c) Raman spectrum of the monolayer MoS2, in which the E2g and A1g vibration modes are located at 383.35 and 402.11 cm-1, respectively. (d) TEM images of the ZrS2 QDs.Fig. 2 Spectroscopic and electronic band structure characteristics of the device. (a) UV−visible absorbance spectra of the monolayer MoS2 and PL spectra of ZrS2 QDs under 360 nm excitation. (d) PL spctra of ZrS2 QDs, MoS2 and ZrS2/MoS2 heterostructures under 365 nm excitation. (c) UV−visible absorbance spectra of the ZrS2 QDs. (d) Energy band structures at the ZrS2/MoS2 heterostructures.Fig. 3 Carrier schematic diagram of the heterostructures. (a,b) The band structure of heterojunctions before (a) and after (b) illumination. (c,d) Energy band structures showing the charge transport schemes along the monolayer MoS2 channel between the two Au electrodes (c) with and (d) without the ZrS2 QDs.Fig. 4 Photoresponse of pristine MoS2 and ZrS2/MoS2 hybrid devices under 365 nm illumination. (a) I–V characteristics of the pristine MoS2 device under 365 nm illumination at various light intensities. (b) I–V characteristics of the ZrS2/MoS2 hybrid device under 365 nm illumination at various light intensities. (c) Dependence of responsivity on incident light intensity for both devices. Fig. 5 Spectral response characteristics of pristine MoS2 and ZrS2/MoS2 hybrid devices. (a) Dependence of responsivity on incident wavelength (b) Dependence of specific detectivity on wavelength