Highly photosensitive AuPd/SiO2/n-Si MIS structure for near-infrared photo detection and energy harvesting

In this paper, a novel type of highly photosensitive narrowband AuPd/SiO2/n-Si Metal-Insulator-Semiconductor (MIS) structure is developed for selective photodetection in near-infrared and energy harvesting. The MIS structure has been developed and optimized, in particular with the growth of a novel type of transparent electrode of 15 nm thick AuPd and the optimization of interface states density (NSS) at the semiconductor/insulator interface (less than 4.109 eV−1 cm−2) via novel surface chemical treatment and the growth of high quality of insulator layer by rapid thermal oxidation, which promotes efficient carriers collection and dark current reduction. Several experimental techniques of structural, electrical, and dielectric characterizations, such as high-resolution transmission electron microscopy (HRTEM), current-tension (I–V) spectroscopy, impedance spectroscopy, and photocurrent spectroscopy, have been combined to characterize and evaluate the performance and the equivalent circuit of this novel type of photodetector. The analysis of the operating characteristics of this AuPd/SiO2/n-Si MIS photodetector has made it possible to specify some particular properties obtained: improved barrier height of 0.8 eV, very low density of the dark current, high photosensitivity greater than 5.102, a wavelength-selective spectral response with a narrow bandwidth at λ = 1.025 μm and linearly dependent on the energy of the light source. These results show that this novel type of MIS structure is very promising for infrared photo detection and energy harvesting applications.