Phototransistors using Van der Waals Heterostructure

Since the photodetectors based on molybdenum disulfide (MoS₂) emerged, diverse researches have been conducted to obtain high performance as the photodetectors.[1] However, it is not trivial to study the intrinsic optical properties of MoS₂ because of the reflected incident light by the generally used opaque substrate such as SiO₂. Here, we report our study of the intrinsic optical characteristics in MoS₂ phototransistor through the transparent device structure fabricated by 2D materials-based heterostructure. The internal photo-responses (corresponding to the photo-response generated by absorbed photons in a MoS₂ sheet) such as responsivity, detectivity, and quantum efficiency were carefully investigated. The measured results indicated that the internal quantum efficiency was not strongly dependent on the wavelength of the incident light, whereas the external quantum efficiency was. Our study helps to understand the intrinsic optical characteristics of 2D-based photodetectors, and will provide an insight for the realization of 2D-based transparent photodetectors.R
eferences
[1] O. Lopez-Sanchez et al., Nature Nanotechnology, 8, 497 (2013).