An alternative method to grow GE thin films on SI by electrochemical deposition for photonic applications

Abstract

Germanium films several micrometers in thickness were electrochemically deposited on silicon wafers for the first time without catalysts and at room temperature from a solution containing Ge species that have been electrochemically dissolved from Ge target. The films were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. SEM images show that the deposited products presented different structures (Flower-like, spheres, and thin films) depending on the current density. XRD reveals that the germanium electrodeposits were of polycrystalline structure and have the preferred crystallographic growth orientation of (220). The grown films were deposited with nickel contact electrodes for characterization as Metal semiconductor Metal (MSM) photodiodes. The current-voltage (I-V) measurements showed the ability to efficiently detect both UV and visible photons. The low deposition temperature, the ease of thickness control, and the inherent advantage of spatial selectivity of the electrodeposition process make this method a promising way to selectively grow high-quality germanium for electronic device applications.