Waveguide-integrated aluminum–MoTe₂ Schottky photodetectors for the wavelength band extended to 2 µm

Transition metal dichalcogenide (TMDC) materials with excellent optoelectronic properties have attracted much attention in the fields of reconfigurable electronic devices, next-generation FETs, and photodetectors (PDs). While normal TMDC PDs have a bandgap-limited absorption edge of ∼1.3 µm, metal-TMDC Schottky PDs based on internal photoemission provide an operation band extension strategy. In this study, we demonstrate that a TMDC PD can even operate at the wavelength band as long as 2.0 µm by judiciously choosing TMDC and metal materials to construct a low barrier height Schottky PD. Specifically, a silicon waveguide-integrated Al-MoTe₂ Schottky PD was measured with responsivities of 18 mA/W and 5.5 mA/W at 1.6 µm and 2 µm, respectively. Meanwhile, the dark current is as low as 2 µA. The linear response can be maintained when the input optical power is in the mW scale. A measured 3 dB bandwidth is much larger than 1.75 MHz. These findings offer a promising avenue for expanding the detection range of the TMDC-based PDs with overall good performance in responsivity, bandwidth, sensitivity, and linearity.