Si₂Te₃Photodetectors for Optoelectronic Integration at Telecommunication Wavelengths

High-performance two-dimensional (2D) - photodetectors with the potential for on-chip integration are desired for telecommunication applications. This work presents the photoresponse of planar silicon telluride photodetector (Si2Te3) with under wavelengths of 1310 and 1550 nm light illuminations. We utilized mechanically exfoliated multilayered Si2Te3 to fabricate back-gated phototransistor. The device with ∼ 50 nm Si2Te3 flack thickness demonstrated a hole mobility of 0.36 cm2 V-1s-1 and photo-responsivities of 170.5 AW-1 (0.35 μW), and 12.1 AW-1 (0.25 μW) at 1310 nm and 1550 nm excitations, respectively. Furthermore, the frequency response of the device with two different metal contacts (Au/Cr and Al/Ti) was tested. The device exhibited moderate broadband response with Au/Cr metal contact of 3dB bandwidth of 1.6 MHz, while 3.8 MHz bandwidth is realized with Al/Ti metal contacts. We also demonstrated a prototype of a heterogeneously integrated Si2Te3 photodetector onto a Si waveguide. The transmission losses in the waveguide were measured before and after the integration. Results demonstrated an attenuation of the optical signal by 24.3 dB and 18 dB for 1310 nm and 1550 nm wavelengths, respectively, that can attribute to the material induced losses. These findings suggest that Si2Te3 is a promising 2D semiconductor material for optical communication photodetection.