Evaluation of crystalline germanium thin films electrodeposited on copper substrates from propylene glycol electrolyte

Germanium thin films electrochemically deposited at 300 K from a solution of GeCl4 in propylene glycol were investigated using X-ray diffraction (XRD), infrared (IR) spectroscopy and atomic force microscopy (AFM). XRD reveals that the germanium electrodeposits are of crystalline structure and have the preferred crystallographic growth orientation [2 2 0]. The presence of the hydrogen bonding in the germanium films such as Ge–H and Ge–H2 is shown from the IR absorption and does not cause a phase transition from crystalline structures to amorphous structures. The AFM images exhibit anomalous surface roughening behaviors in growth that deviate from statistical surface growth models and indicate a transition from rough surfaces to smooth surfaces.