Fabrication and Characterization Study of Porous Silicon for NIR-VIS Photodetector Applications

In this paper, photoelectrochemical etching of the n-type silicon (n-Si) wafers is used to prepare porous silicon (PSi) with current density of 10 mA center dot cm-2 for 10 min. Moreover, the structural and morphological properties of the n-PSi were analyzed by using XRD and AFM, FTIR and PL. XRD patterns of PSi show that the films are single-crystalline, with cubic structure. The major peak characteristics are allocated to plane (004). The atomic force microscope image and the distribution chart of the grains of the n-PSi displayed that the grain sizes were -8.98. FTIR is a powerful and easy-to-use technique to obtain the surface chemical state of PSi. The convenience results from the transparency of silicon for IR light and the high surface area. The basic features begin from the knowledge of the bondings to hydrogen, [Si-H], and to oxygen [Si-O]. The model calculations sometimes provide useful information in the assignment. By examining FTIR, the active bonds showed the formation of PSi. PL spectra were measured in the range of (600-900) nm, the emission peak for the fixed excitation wavelength at 500 nm, and spectral 1.78 eV and 1.24 eV. PSi is recognized as an attractive building block for photonic devices because of its novel properties including high ratio of surface to volume and high light absorption. We first report NIR and VIS (PDs) fabricated by PSi as a carrier collector and a photoexcitation layer.