Development of an ultrafast photo-switch device using surface passivated nanocrystalline CdS thin film

Enhancing Photodetection Performance and Thermal Tolerance of CdS Thin Films through Cobalt (Co) Doping

“…The thermal tolerance of the photodetector device was monitored by measuring the photo‐responsive ( I p / I d ) characteristics of pure and Co‐doped CdS thin film‐based devices under continuous ON and OFF pulses (width 60 s each) [ 31 ] (as illustrated in Figure 4a) of blue light at various operating temperatures (27, 35, 50, 65, 80, 90, and 110 °C) and constant operating voltage of 10 V. The setup used for this measurement is shown in Figure a consisting of a photodetector device mounted on a PID controlled heating stage, a blue LED (of intensity 1 mW cm −2 ) connected with a pulse generator to generate light pulses each of 60 s ON and OFF cycles. By following the incident light pulses, the photoresponse of a pure CdS device, measured at room temperature (27 °C), shows reversible photo‐switching ( I d à I p and I p à I d ) behavior [ 45 ] (as like shown Figure 4a) with the I p / I d ratio of ≈23. Now as the operating temperature increases, this I p / I d ratio increases exponentially to ≈230 (with 90% variation) at a temperature of 110 °C (as shown by the black color columns in Figure 5b).…”