Narrowing Bandgap of HfS2 by Te Substitution for Short-Wavelength Infrared Photodetection

Infrared photodetectors are widely used in the field of remote sensing, communications, biomedical imaging, etc. Most photodetection based on 2D transition-metal dichalcogenides (TMDs) is limited to the visible (Vis) to near-infrared (NIR) due to large intrinsic bandgaps (approximate to 1.2-2 eV). Here, a bandgap engineering of HfS2 by a tellurium (Te)-replacement strategy is obtained via chemical vapor transport method. The bandgap values of HfS2(1-x)Te2x decrease from 1.7 to 0.88 eV with Te composition changing from 0 to 0.095. Few-layer HfS1.81Te0.19 based field-effect transistors exhibit a high current on/off ratio of 10(6) and decent electron mobility of 12.6 cm(2) V-1 s(-1) at room temperature. The photodetectors show a responsivity of 2 A W-1 with a remarkable photocurrent of approximate to 3 mu A and a fast response speed of 8.8/75 ms at 830 nm simultaneously. Further, the response spectrum of HfS2(1-x)Te2x based photodetectors is broadened from Vis to short-wavelength infrared (SWIR), covering the free-space laser communications wavelength and the second NIR region in medicine. Bandgap engineering of 2D TMDs proposed in this work offer a promising route to develop bandgap-variable 2D materials for infrared photodetection applications.

Automated summary

This study successfully engineered the bandgap of HfS2 by introducing a tellurium (Te) replacement strategy, expanding the response spectrum from visible light to short-wavelength infrared. This provides a new route for the development of infrared photodetectors.