Study the aging effect on the optoelectronic properties of HgI2 nanorods /Si heterojunction photodetector

The significant variation in the properties of optoelectronic devices with time due to the degradation in their materials represents a very important issue. This will allow us to make a decision to select an appropriate device for long-term operation that can withstand harsh environments. In this work, we studied the variation in the optoelectronic properties of the HgI2/Si photodetector during the aging process under normal ambient conditions (6 months of storage). The HgI2/Si photodetector is prepared by laser ablation in ethanol at a laser energy of 0.5 J. The XRD studies confirm the formation of orthorhombic β-HgI2. The TEM image of HgI2 NPs confirms the formation of the nanorods morphology with an average diameter of 33 and 106 nm for freshly prepared and stored samples, respectively. The electrical characteristics of fresh and stored p-HgI2/p-Si photodetectors, including the current–voltage in the dark and under illumination, were investigated. The dark I–V characteristics of p-HgI2/p-Si reveal that the forward current decreases and the reverse current increases after 6 months of storage at normal ambient. The ideality factor of the heterojunction increases from 2.9 to 6.1 after aging. The illuminated I–V characteristics show that the photocurrent is reduced by a factor of 1.97 at 180.1 mW/cm2 light intensity and − 4 V after storing. The responsivity decreases from 3.39 to 1.57 A/W after aging, as well as the detectivity and EQE decrease from 11.2 × 1012 to 5.2 × 1012 Jones and from 9.3 × 102 to 4.3 × 102%, respectively. The minority carrier lifetime of the photodetector decreased from 83 to 50 µs after the aging process. The photodynamic ON/OFF ratio and current–time characteristics are demonstrated.