  Multilayer van der Waals (vdWs) semiconductors have great promising
application in high-performance optoelectronic devices. However, the
photoconductive photodetectors based on layered semiconductors often suffer
from large dark current and high external driven bias voltage. Here, we report
a vertical van der Waals heterostructures (vdWHs) consisting of multilayer
indium selenide (InSe) and tellurium (Te). The multilayer InSe-Te vdWHs device
shows a record high forward rectification ratio greater than 107 at room
temperature. Furthermore, an ultrasensitive and broadband photoresponse
photodetector is achieved by the vdWHs device with an ultrahigh photo/dark
current ratio over 104, a high detectivity of 1013, and a comparable
responsivity of 0.45 A/W under visible light illumination with weak incident
power. Moreover, the vdWHs device has a photovoltaic effect and can function as
a self-powered photodetector (SPPD). The SPPD is also ultrasensitive to the
broadband spectra ranging from 300 nm to 1000 nm and is capable of detecting
weak light signals. This work offers an opportunity to develop next-generation
electronic and optoelectronic devices based on multilayer vdWs structures.
