Incorporation of Zinc Oxide on Macroporous Silicon Enhanced the Sensitivity of Macroporous Silicon MSM Photodetector

Abstract

In this study, metal-semiconductor-metal (MSM) photodetectors (PDs) was fabricated on the macroporous silicon substrate, (mPS) followed by growth of zinc oxide (ZnO) on the mPS substrate (ZnO/mPS) with addition of nickel (Ni) contact in finger mask pattern. The mPS was formed by electrochemical etching technique with an estimated etching time of 15 min by a continuous current flow of 25 mA. The ZnO nanostructures were synthesized by cost-effective chemical bath deposition (CBD) process. Field Effect Scanning Electron Microscopy (FESEM) and X-ray Diffractometer (XRD) revealed the randomly distributed of upper-morphologies and crystalline properties of x-shaped mPS as well as the distribution of ZnO/mPS. A good Schottky contact with superior photoconductivity, photo-responsivity, and photo-sensitivity have been demonstrated from these MSM PDs under illumination of 383 nm and 422 nm light sources. An enhanced photoconductivity at 422 nm had been demonstrated from Ni/ZnO/mPS/Ni PD which was believed due to the incorporation of energy properties at ZnO/mPS interface with a greater energy band gap of 3.15 eV. The responsivity of Ni/mPS/Ni PD at 383 nm and 422 nm were 0.088 A W−1 and 0.171 A W−1, respectively. While the Ni/ZnO/mPS/Ni PD shows the double photo-responsivity for both wavelengths, with the values of 0.160 A W−1 and 0.385 A W−1, respectively. In overall, the incorporation of ZnO/mPS structure drawn a great significance in PDs performance due to unique tunable photo-responsivity, higher sensitivity, and faster rise and decay time which attributed to the swift recombination process.