Photodetectors based on porous silicon produced by Ag-assisted electroless etching

Porous silicon (PS) produced by electroless etching method was used to form Au/PS/p-Si/Pd structures. PS was produced from p-type silicon by Ag-assisted chemical etching in 22.5 M HF–0.05 M K2Cr2O7–H2O solution. The etching time was varied from 30 s to 20 min. These structures were electrically characterized by recording the I–V characteristics, which show an increase of the rectifying characteristic with etching time. Extracted parameters from I–V characteristics such as ideality factor and series resistance as a function of etching time were studied. The responsivity and the quantum efficiency of these structures were determined in the 350–1100 nm wavelength range. Finally, it was shown that the maximum sensitivity of the device is at a wavelength about 425 nm.