High-performance, broadband, and self-driven photodetector based on MoTe2 homojunction with asymmetrical contact interfaces

The van der Waals junction of two-dimensional materials has the characteristics of weak interlayer interaction and strong light–mass interaction. The internal electric field formed at the interface of Van der Waals junction promotes the separation and efficient transfer of photogenerated carriers, showing the characteristics of low power consumption, self-drive, high responsiveness, and ultrafast response. Therefore, we fabricate a transverse homojunction photodetector by mechanical stripping. Furthermore, considering the influence of the contact between the two sides of the metal electrodes, we select the metal electrodes corresponding to the matching work function according to the Fermi level with different thicknesses of MoTe2, and two anti-barrier layers are obtained. Finally, a transverse homojunction self-driven photodetector with Au-thin MoTe2-thick MoTe2–Ni/Au structure is fabricated, which improves the photosensitivity and response time, and broadens the spectral detection range. When Vds = 0 V, the rectifier ratio increases to 4.6 × 103, which is 50 times higher than that of symmetrical electrode homojunction. Under zero bias voltage, when the spot area is 3 × 10−9 m2, the photosensitivity reaches 28 mA/W (637 nm), the response time is 38.83/40.17 μs, and the infrared detection is extended to 1550 nm. It has potential applications in optoelectronics and optical signal detection.