  Two-dimensional (2D) material photodetectors have gained great attention as
potential elements for optoelectronic applications. However, the linearity of
the photoresponse is often compromised by the carrier interaction, even in 2D
photodiodes. In this study, we present a new device concept of dual-floating
van der Waals heterostructures (vdWHs) photodiode by employing ambipolar MoTe2
and n-type MoS2 2D semiconductors. The presence of type II heterojunctions on
both sides of channel layers effectively deplete carriers and restrict the
photocarrier trapping within the channel layers. As a result, the device
exhibits robust linear photoresponse under photovoltaic mode from the visible
(405 nm) to near-infrared (1600 nm) band. With the built-in electric field of
the vdWHs, we achieve a linear dynamic range of ~ 100 dB, responsivity of ~
1.57 A/W, detectivity of ~ 4.28 * 10^11 Jones, and response speed of ~ 30
{\mu}s. Our results showcase a promising device concept with excellent
linearity towards fast and low-loss detection, high-resolution imaging, and
logic optoelectronics.
