Characteristics of Thermally Treated Contacts on Porous Silicon Based Metal-Semiconductor-Metal (MSM) Photodetector Structures

To date, little work has been done on porous silicon-based MSM photodetectors. Porous silicon (PS) was obtained on n-type silicon (111) using photoelectrochemical etching in HF. Microstructural investigation has been done by scanning electron microscope (SEM) and X-ray diffraction (XRD) measurements. We have found that the PS consists of a regular silicon microarray with triangular geometry. From the X-ray diffraction scan, PS shows a broadening of the full width at half maximum with respect to the as-grown epilayer. In this work, PS-based MSM photodetectors (photodiodes) with nickel (Ni) Schottky contacts were fabricated and characterized. The application of thermal treatment to the contacts at various annealing temperatures (500-700degC) was investigated. Electrical characterization was performed by current-voltage (I-V) measurements. Morphological characterization was performed by atomic force microscopy (AFM) measurements.