Optoelectronic Characteristics of Tungsten Disulphide Based Visible Range Photodetector

In this work, tungsten disulphide (WS2) based heterojunction photodetector device is fabricated on top of silicon (Si) substrate by using simple drop casting method. The device is characterised for its optoelectronic properties in the visible range of light illumination at 465 nm. The current-voltage (I-V) measurement is performed to attain I-V curves of various laser powers (282.6 μW, 589.2 μW, 889.9 μW, 1.07 mW and 1.265 mW). The photocurrent is found to be highly dependent on the laser power. Time based responses are calculated at 3.0 V DC bias voltage for various modulation frequencies (1 Hz, 50 Hz, 100 Hz, 500 Hz, 1 kHz, 3 kHz and 5 kHz). The fabricated device has high responsivity of 66.85 mA/W for an incident laser power of 1.265 mW and detectivity of 1.1763 × 10
⁹
Jones for an incident laser power of 282.6 μW. Raman shifts are observed at 351.38 cm
^-1
and 420.54 cm
^-1
, confirming the successful growth of WS
₂
and verification of a non-stoichiometric WS
₂
layer by the energy-dispersive X-ray (EDX) spectroscopy. These results are very promising towards further development for optoelectronic applications.